I've had very good luck with Best Gaskets. To be fair the engine Mart built far exceeded factory specifications. When you modify something you can't expect other parts made and designed for normal use to not fail.
We use to coat the head gaskets with a light smear of wheel bearing grease. Made them easier to remove later when we decided to do something else on the car.
It was a matter of no money for us teenage hot rodders. We had to gather 13 pop bottles to get enough cash for a gallon of 26 cent gas. lol Chap