Definitely agree with benefits of an overdrive though there are a few ways to get it behind an FE...gear vendors gear box, NV4500 (with adaptor), Tremec tkx, Ford 6R80 (with controller and adaptor). None are cheap but all have their benefits.

 

Thanks guys for all the great info. I appreciate it. I'm going to have a tough choice on how to move forward. A friend asked me if this was my dream truck and if it was he could see me justifying putting a lot of money into a swap. And all the things that come with it. His advice was, if it's not my dream truck, then make it reliable for cheaper. I love the truck and the only main reason I bought it was how clean and original it was. I picked it up for what I think is a decent price here in CA. Could I flip it? Sure but I would then be looking again for another clean truck. And honestly I don't know what a dream truck of mine is. I just love old Fords.

 

There are a number of things you could do that would make it more reliable and still prepare for EFI. You could do a 3G alternator swap with the benefit of stable output and better lighting at night. Next, you could work on an in-frame tank with in-tank pump. This would replace all of the old fuel lines and give you stable pressure at the carb. With the correct return-style regulator you can drop the pressure to 4 to 6 psi for the carb and bump it up to 60 psi for EFI. Pull the distributor cap and see if it still has points or if a Pertronix Ignitor has been installed. If still points, upgrade to the Pertronix since points and especially condensers are of dubious quality today. While in there, replace the wires and inspect check for side-play of the distributor shaft/rotor. Pertronix has some nice drop-in options that work great and can be used with an EFI swap initially before going to timing control. You'll get better starts and more consistent performance with electronic ignition that Pertronix provides. These are relatively low-cost upgrades that will not hurt and will potentially enhance the value of the truck along with better reliability. Then you can move on to the intake manifold, exhaust, etc., that need to be upgraded to support EFI. Properly selected you'll see improved performance and possible economy improvements. When you're all finished, you may find that that 390 is more than adequate as-is.

I do some support on the Holley EFI forums and have seen exceptional installations by shops and some that required nearly starting over again. If you decide to move on with an EFI install, find a shop with EFI expertise and who can provide references. A good shop will do a proper installation and will provide a good solid baseline tune. Contrary to all the marketing, Edelbrock, Holley, and others require some additional tuning/optimization.