They will work with a factory 68-71 piston, you need a thicker head gasket. Can't use the one they suggest. A .055-.060 gasket would work OK. Pretty fricken simple, no?
When do I get paid to solve these mind-boggling issues?
We run Edelbrock closed chamber heads, and the piston sits out about .022 on a 340 and i wanted the compression to be 10-1, 1 set of cometic gaskets at .066 and we are in business.