Which is about 6spi more than yours

Sorry to hear it paul, you sure its the H/G and not something else? get a leak down test and compression test done to confirm before taking the head off.

Is it possible the cheap motor factors H/G has corroded while its been sitting in storage and then you take it fo a blast and pop.

IMO you can't beat the std ford headgasket, would be perfect for your needs (was fine on my RST )