They are all pretty close. I put a 455 in a 75 Skylark that had a V6. I only had to do on thing to get it to work. The adjuster rod for the alternator was not correct. I had to weld a bit on the bottom that bolted to the water pump because it was too tall to connect to the alternator and the AC bracket otherwise. Even the lines worked. I know it is the stubby round compressor vs the long one but it should tell you the brackets are very close and you can get it to work unless you want an all original setup.
All Parts are that same as Mentioned by Gregg. The Pulleys are a different story however. If you already have AC pullies for a 455 then you are set. If you have the 455 Arm Gregg mentioned you are all set. Make sure you use stuff from all the same year.
