blown 2 head gaskets

UPDATE: I switched to SCE copper gaskets, cleaned all services with brake cleaner, used a thin film of black RTV around all port holes. I put a new o-ring wire in the problem cyl. The problem head was shaved in the mill, (NO STONES). I also crossed the heads so the old #2 cyl is now on #7 cyl. Ran on the street a few times and all seems good, I will post after next time at the track Sept. 10th. Thanks for all the time and advice.