If u have the piston .019 -.020 out of the hole and use a .025-.039 head gasket ..then mill the head to end up around .022-.030 deep on the shallow side of the chamber... Suprise...you have quench. You can mill the heads just to closed, but the chamber will be in the 48-52 cc range. I have seen where some guys have milled beyond just making the closed chamber and end up finding a thin spot and making a hole out of it. But I have j heads that are at the .030 deep shallow side and they run great and spec to 60 cc's