I am doing something like that now. It is a 66 k10 chassis going under a 66 c10 suburban. Unless you REALLY know what you are doing with drivetrain(s), put the whole frame under it. While you are at it, steam clean it and soak it with semi gloss black. With air tools, I can strip a truck in 4 hours. Their is quite a bit of difference in the 2 and 4 wheel drive frames, even the motor mounts are different. If you get the front in wrong, it will drive like doo-doo.