Me and my brother did an Lt1 into a mid 80's Firebird and it didn't take any modifications other than, engine mounts, EFI/wire harness. And later we put an LT1 into a Mote SS after it blew a 383, and had a 454 in it... And again I don't remember any mods to the pulleys, accessories, etc. But my brother sold that car before it ever got put on the road.