My paper gaskets between the headers and heads burned out and I bought a set of copper gaskets. The problem with them was the openings were oval and not square like my heads. So instead of filing to make square, I searched around and found a set of Holley 2 layer thickness aluminum gaskets with square holes that lined up perfect with my trick flow heads. I'll get the part number tonight and post tomorrow. I do have to check to make sure tight ever so often. Used red RTV where headers meet collector. No problems.
Bob