[Flathead Fever]

I was a professional mechanic. We used Permatex head gaskets they had a coating that heated up and made the seal on the head gaskets. You do not coat them with anything. They were designed with materials that could handle the expansion and contraction of the cast iron block and the aluminum heads. I would do exactly what the original gasket manufacturer recommends. Clean the surfaces really good and make sure the surfaces are straight. I have a machinist's straight edge I check the block and heads with.