Converting to 4X4

[73CheyenneSuper20]

i have a '73 Super 20 2wd longbed, 454 w th400. I'd like to make it into a 4x4, so I've been reading as much info as I can from here. It looks like it is best to get all the parts from 1 donor truck, and somebody suggested to just trade the frame, and everything attached to it (axles, tc etc). The very front of my frame is a little bent, nothing major and probably fixable.

The questions are: Is this a good idea? If i was able to get hold of one of those military Chevys M1008, would I be able to put my cab and bed on that chassis? Even though they seem to be '84-'86. I have a great engine and trans, so I want to use those.

The reason why: Here in California, '75 and back are smog exempt. I am looking for something with a good drivetrain, but bad engine/trans/ back registration fees etc. I'm also looking at a '76 project of somebodys on Craiglist, missing parts and has 4 years of back registration.

How does it sound? Input welcome...
I'll definitely have to take pics on whatever I do.