Chances are that your 1975 Ford 460 has D3VE heads on it. The casting number on the heads is on the outside of the head, and between the top of the thrid and fourth exhaust ports. Should be D3VE-A2A.

If you have these heads, then I would suggest putting in flat-top pistons. The engine (assuming oem) has dished pitons in it and your current compression ratio is in the neighborhood of 8:1. Flat top pistons will bring you just over 9:1 and you may still run pump gas. This compression ratio will work well with your ported heads and other associated components mentioned in your post.

Paul