Ben, I know you are excited about your new truck, but I'd suggest you slow down and take a breath before you start tearing everything apart on it without rhyme or reason. Drive it as is (repair as little as possible that is absolutely needed for safety only) to get to know the truck and get a better understanding of what it needs and what you want.
It sound like you are not experienced with building a hotrod or whatever you would like to call your truck and want to make changes without really having a good understanding of what that entails or what the results will be.
First lets look at the steering. You say there is a lot of freeplay, but you don't know where the looseness is located. A recirculating ball steering box like the Chevelle seldom gets loose from wear. I'd look elsewhere for any looseness first. You need to put it on a drive on lift or take it to an alignment shop and have the whole front end checked out for wear and proper alignment, wheel bearings, ball joints, tie rods and drag link, idler arm. The steering column to steering box connection also needs to be checked for wear or slop. If there is an intermediate shaft, it needs to be checked for whip and/or flex. Finally the column itself needs to be checked for wear. Worn tilt mechanism can be evaluated by grabbing the steering wheel by the rim with the truck parked and trying to move it side to side, up and down with the tilt locked. A small amount of up and down play is not a serious concern, but there should not be any significant side to side movement. GM columns are noted for wearing in the tilt mechanism, but they are fairly easily rebuilt for a lot less expense and work than replacing it. There are rack and pinion steering box conversions made for Chevelles, but they are pretty pricey and of little improvement. If your steering box does have slop in it and the pump is full of fluid, it can be adjusted, but it should be done by someone who knows what they are doing or it could accelerate the wear and/or cause the box to stick and bind.
Next you need to determine what rear axle ratio you have and measure the diameter of the rear wheels. If you don't know how to determine the axle ratio, look on like for how to do it or take it to someone who does know how to do it. Without knowing the rear axle ratio and tire diameter or having an accurate tachometer you really can't determine how many RPM the engine is turning at a given speed and what can be done to change it. Seldom does changing the transmission change the engine speed unless you going from a non over drive to an OD tranny, but changing a tranny is also an expensive project.
Bags IMHO is a LOT of money and work just to impress people when it is parked. To most people it says this guy has way too much money he doesn't know what to do with. You say you understand how to control airbags, but know little to nothing about how they are installed? The right way to control bags is to use computerized controls and sensors, That type setup costs several thousand dollars NOT including the bags, compressors, tanks or installation. Do you have a good long term (what you are proposing is going to take months if not years to accomplish assuming you have the funds readily available) workshop with a large assortment of tools and equipment, and have mad skills in fabricating and welding?

 

First,Thank you for your help, and for you time.

I'm actually a professionally trained mechanic, and i own about 15k worth of Snap-On tools.

I will admit that i am no expert in hot rod, as the 55 is my first one,

My background is most high end europeen performance (AMG, GTIs and other M3s), with would explain my lack of knowledge on steering boxes and/or other leaf springs.

I have a full understanding of what an air ride implies, i "baged" a few casr and wagons myself using the top of the line management form accuair, bagrider and air lift.

I do have a lack of fabrication skills, witch i hope this truck with help with.

I know for a fact the tilt is complexity worn out, i was not aware of replacement parts for such, thank you for helping me there.

I was interested into the rack and pinion setup against steering box in order to eliminate moving parts and maintenance on the long term.

This truck is going to get a full re-spray, bags, a entire custom harness (my specialty) and also more creature comfort such as, A/C, soundproofing ect...

I cant wait to get started, i sold my M5 to finance this bad boy, i have about 8k waiting to be spent !

 

OK, Ben had I known your background earlier, I would have had a different conversation. We get a lot of dreamers and clueless that get a "new" truck and want to tear it all apart and change things ***** nilly for reasons like "I saw it in a magazine" or "everyone says that's what it needs". Who seem to think building a hot rod is like building a plastic model kit, everything will just fall into place.

 

Updated the first post ! With my timeline list.

 

that's a damn nice truck Ben. good luck with it. But like has been said. drive her some and let her tell ya what all she wants.

 

Thank you,

I drove her plenty, i got her 4 years ago

 

OK Ben let's talk.
How low do you want to go with the bags? Layin running boards? are you going to drive it much or just show it?
I'd just pull the column and put in an Ididit with your choice of wheel.
If the steering is still loose I doubt it is the box, more likely the steering link/ball joints. Before i spent alot of money rebuilding the front end, I'd consider finding another frame and installing an aftermarket IFS like from Heidts or Art Morrison, the Chevelle leaves a lot to be desired, many guys with Chevelles are pulling them out and replacing them. Secondary benefit is you could be building the new chassis while driving the present one then just swap over the sheet metal.
AFA a tranny, what rear ratio do you have now and do you prefer a stick or an auto? How hard are you going to beat on it? What size wheels and tires you planning on running?

 

So, it is going to be a driver cars, not trailer queen, i plan on driving the truck a lot.

I would like to lay the running board on the ground. i want to get rid of the racked look.

I don't think i will replaced the frame, that would be more like a full restoration project, witch i'm not looking for at this time.

FYI, i think that the steering box is the original box for the 68 chevelle. Thats why I'm putting my money on it.

I'm going to stay with auto, and it wont be driven very hard, mostly cruising, I'n not sure about the ratio, how can i find out ?

I'm thinking 17s or 18s with low profile tires

 

Laying frame (or running boards) and extended driving are nearly mutually exclusive, IMHO
To determine the rear axle ratio, jack up the rear axle so both tires are off the ground, the truck is in neutral and you (or an assistant) can count the pinion rotations. Mark a tire with a chalk or tape and rotate it exactly 10 times while counting the pinion rotations (it may help to also mark the pinion or drive shaft). Divide the number of pinion turns by ten to get the axle ratio i.e. if the pinion turned 37 times your rear axle is 3.7 : 1. Hint: if when turning the one wheel the wheel on the opposite side turned in the opposite direction you have an open rear axle. If both wheels turn in the same direction you have a limited slip or locker type rear axle.
Once again, a recirculating ball type steering box does not usually wear much, especially power steering. That's what makes the Toyota PS box such a popular swap with the stock axle, the Toyota box is a recirculating ball design. The wear points in a RB box are adjustable. I'd suggest getting a shop manual for you year Chevelle or search the internet for the proper adjustment procedures before replacing your box.

 

Bulding a 56 and have a few pics that might be helpful.


Tim