From what I understand about the 1/2 ton transfer, depends on which one you get, some will require notching the frame rail to get enough room for it to fit.
I have read on TRS about people installing the engine and drive train from full size into a RBV, but don't remember what all had to be done to make it fit. It did not sound like it was a bolt in, and took lots of modification.
You might check here:
These folks have been working with older RBV's forever, if it can be done they will know how, or they can steer you in the right direction.