I put a GTO LS1 in my 78 Camaro.
Couldn't get the AC unit to fit without notching the frame.
So I ousted it. Also the GTO alternator is bigger I was told and
it was hitting my pittman arm, so we had to relocate it.
There's places that sell AC relocation kits.
Go on Nastyz28 and research the High Tech Retrofits section.
I put up most of the info on the swap info sticky.