Steve, I thing since your wallet is clamped shut that you use the 3/4T chassis that you have handy. The center section can be used on the existing rear if you want to change gears.
I myself would look at the C3500 front end at the salvage yard, however that is me.
I agree that the Caddy would be fine for a 1/2T, however I believe that you intend to load the crap out of it when your done and will need the extra heft of the 3/4T or 1T parts.
That being stated, I think you are on the bleeding edge of the swapology here and are on your own. There are plenty of 1/2T swaps, S-10 swaps, however the 1Tons that have been done are on P30 chassis with straight axles.
