I had the same problem with my 360-410 stroker. I finally ended up milling .030 off the top of the quench pad to get it to stop blowing gaskets. They blew into the valley area. It didn't matter what head gasket I used it didn't help including cometic. It was getting expensive and very agravating. Milled the pad and haven't had another gasket bolw in 3 years of racing.