My apologies in advance if I may have missed it ... but what engine / trans was in the car originally?
The 240 (6 cyl) and 289 (V8) mave have had similar mounting systems (engine and frame mounts) and bell-housings, but the FE engines used different mounts, radiators, and bell-housings for sure ... quite possibly even different transmissions and driveshaft lengths.
Radiators had hose connections at opposite sides on the 289 vs the FE.
FE Motor Mount
289 (and 240?) mount
It looks like C4 or FMX for the 240/289
and C6 or FMX for the FE engines.
Not that swapping all of the above is not possible ... just that the OP might want to know this going in.