if its an original 2bbl eng its a 429, all early 460s had 4bbls. the heads are the smallest combustion chamber and do real well with f/t pistons. while you are at it pick up 30 more cubes by adding a 460 crank. that is if you are going to change pistons. bore it .060 and have more cubes. i think .090 makes it a 477. have built several with those heads and .060 bore.