I could see getting 3-4" by tipping the tops of the spring buckets out, RA brakets will probably have to be fabbed up,

 

ok time for a reality check here, and some suggestions since this has gotten into a lot of suppusition, and speculation.
First things first-find a ranger or whatever your gonna build for this becuase until you know for sure what you have to build on none of the specifics are going to make a difference. talking about the idea is ok but getting into specs is a waste of time at this point because we don't have the truck to start with or take measurements off of. Trust me on this I had a general idea what I wanted to do with my ranger but until I got the body, and frame to the house I couldn't sit down, and figure out exactly how to mount it up.
Now you know where you have axles sitting, but go out, and find a ranger or whatever that you think you would like to use and it doesn't have to be a 4x4, or even have an engine in it.
Next find your engine so you can decide what exactly has to be done to it and a trans also, you might find out when we start putting stuff in and measuring things that the BW tcase won't fit (I don't know just a what if) and you would have to run with something like the np207
last thing is your talking putting fullsized axles under a ranger which is fine, but this makes it non street legal so it will have to be towed to the races which adds the expense of having a trailer at this point in time plus your talking about selling your pickup for a car so I have to ask how you plan on getting it to the races?
Now I am the last person in the world to try, and talk someone out of this, and I am not talking you out of getting into the mud drags cause I would like nothing better than to see you get into it but even I didn't start in modified with the truck I currently have. But what I don't want to happen is to have you get started on building someting up, and not having the money to finish it, and not get to race it then get discouraged, and give up. So my suggestion is if you want ot play with a ranger then find a running one that is 4x4 preferably with an auto since sticks don't do well in the drags as you seen then you can do some work on it and buy a second set of rims to run the swampers on so you can change them once you get to the track maybe do some things to lighten it up, and play one year in the 4 and 6 cyl stock class, and maybe move upto the street stock class too this will give you a cheap truck to drive around (but don't make it your only daily driver cause if it breaks your in trouble then) and will get you a starting place that you can work off of later as the funds allow, plus will allow you to get a feel for racing and what it takes to win, and how to drive.
I am telling you all this cause it don't take long to dump a lot of money into these trucks, like mine for example not including hte cost of the 351c I was running last year (which would add around $8k to the total) I have over $16,000 into my truck as it sits, now yes $11K of that is the engine but that is still $5,000 into the rolling chassis.