Welcome! Listen to these guys, they know what's up. As stated, 301, 350, 400, 455, all need the 301 mounts and perches to fit these cars. After you get the correct mounts and perches you will need to find a way to bolt them to the frame. Here's where it gets interesting. My '81 Malibu was hopelessly Chevy, but my '83 Bonnewagon had the frame holes in the exact right places! Even though the last 301 was used in '81, there they were, and you should be as lucky. If not, then the best way is to drop a short block w/trans in and line everything up. Then either tack weld the mounts in or spray paint them for later re-orientation. Then remove the motor and drill holes for the mount bolts. That's what I did on the Malibu. Now, getting at the inside mount nuts is a b*tch. If the lower control arms are out, you can get at them through there. I chose to cut an access "window" in each front side of the frame so I could stick a long box end wrench in with the nuts taped on, easy peasy. Cooling- a 400 runs hot but mine did just fine with a 3 row brass 6 cylinder radiator. Better is a V-8 style 4 row equivalent single row aluminum radiator like RockAuto sells. A good fitting fan shroud is mandatory and most V-8 models fit the Pontiac motors, I'm using a Monte Carlo 305 model. Pontiac exhaust manifolds made '70 and later will fit our frames because the steering is in front of the axle after '69 and they dump to the rear. I have a manual trans in my wagon and again, Firebird clutch linkage fit with no trouble. The Malibu I had to sledgehammer the floor to get my Pontiac things to fit. Any more questions this is the right place to ask.
