The bore may be the same but i'm not going to buy a piston only to find out the wrist pin diameter or location is different. We could get a high compression piston made through any piston manufacture but all that I have talked to will build only a minium of 4. I only need one lol. So thats why i'm doing it in the head. Plus i'm glad I pulled the head when I seen how bad the valve seats looked from our lovely ethenol fuel.