grif

i recently bought a 92 1500w/t. it runs decent, but i was wondering about swapping out the 4.3 for a 305 or 350. I need to know what is involved, I heard something about the motor mounts need to be relocated,fan shroud changed,and comp.programmed.I haven't seen anything on the truck that resembles a computer. Can someone tell me where I might some info on this or give me some sort of idea of what i would be getting into? Thanks.