Engine swap questions

I have a 84 coupe deville with the 4100(yeah I know their shitty thats why I wanna swap it out) My questions are Can I swap a 5.7 engine and tranny( computer if I need it )from a 92 fleetwood into it with no problem or would their be alot of changes mounts computer etc. Or either a 5.3 or 6.0 vortec engine Ive seen then dome just have never seen the price on them. And afyer the swap will the stuff that works off the vacum still work like e brake heat and ac. I know the ac would probly be switched over with the new engine but just curious about how the vacum will work.I know a chevy 350 is another option Ive heard do those just bolt right up to the tranny and im set? If so what year 350s would fit ..Thanks in advance