3/4 ton vs 1/2 ton dilemma

[Buick455]

Well I bought a 1986 parts truck for $900 which is a 1/2 ton silverado. The truck has rust thru at the cab corners and in the bed but it is repairable and much better than my 87.
My dilemma is that I purchased brake parts (rotors, master cylinder, booster, priority valve, calipers, lines) and rebuilt my 3/4 ton front differential and axles, steering box, and cleaned and painted the front of the 3/4 ton frame before buying this 1/2 ton truck. Some of the parts can be used on the 1/2 ton but not all of them. I am not sure yet if the front axle gear ratio of the 1/2 ton and 3/4 ton is the same but the rear ratio of the 1/2 ton if 3.08, should I assume the front is the same?. The 3/4 ton is 4.10 if I measured is correctly.
The 1/2 ton has a rebuilt posi rear differential and rebuilt 700R4 trans and the rest of the running gear looks good but the engine is shot and there is so much oil under the front end I am not sure what is leaking.
I decided to pull the engine (new GM EFI engine) and trans (rebuilt 350) from the 3/4 ton as I needed to put new seals in the trans anyway. I am thinking about using the 1/2 ton frame and body with some cleaning and repair but I am not sure if I would like to use the 3/4 ton axles or stay with the 1/2 ton. The 1/2 ton also has new tires. Which I do not have with the 3/4 ton. I am also not sure if I want to stay with EFI from the 87 or go with a carb from the 86. I like the EFI but I have to strip the wiring from the 87 and put on the 86.