[Excaliber]

4.250 bore on a 427 is actually a .017 over bore. Due to the thin wall casting of a 427 it's pretty common to bore in .003 increments. 4.250 pistons can be purchased via the web, no special order required, in various dome/dish configurations to allow for various compression ratios. Typcial 428 crank in a 427 block (stroke 3.980) requires a piston with a non stock pin height, also readily available via the web.

4.25 bore/3.980 stroke = about 454 cubes.

Nice motor!

NOT saying THIS motor is stroked, just a typcial application found in a lot of 427's.