2wd bodyto 4wd chasis

[rusted75 half ton]

Hello all,I was wondering if I had a 69or70 2wd 350 4spd manual truck with a good body and wanted to transfer it to a 67-72 4wd chasis what problems would arise.I'd imagine that a high hump would be need to be bolted on,would I be able to keep the 350 and just hook up a new 4spd manual thats set up for a T case?

Thanks for any response