I figure about .006"/cc on a small combustion chamber, so about .021" to keep it at 11.25:1. If you leave them at 71.5cc and 10.83:1 compression, and your engine makes 600HP @ 11.25:1 compression, you will be all the way down to 598HP @ 10.83:1. Mill them SOBs to 64.5cc so you can get 602HP.
