The picture of that motor is pure sexy. Sounds like you have a plan the one thing I would suggest is to go 455 if you can it will be easier to get the numbers you are looking for and you can do it with a lower state of tune than a smaller cube motor. By the way Ames performance engineering will have just about anything and everything needed they are out of New Hampshire and specialize in Pontiac only. I know the rust in the floors is disappointing but here in the North East that body would be a major find in that good of condition.