I should have been a bit more clear - it seemed like the bolts were bottoming out as they got hard to turn and I could see that the manifold was no where near being drawn up tight to the head. I twas bottoming out against the block.
Doubling up the gaskets may work and I'll check that this morning. And if it is not tight enough, I may try a triple gasket.
Last night I had come to the conclusion that I would silver solder (braze) spacers to the manifold. While more work than welding, having the torch in my hand while I worked would allow me to keep the whole piece warm while I worked which would hopefully minimize warping. When finished, I would have buried the piece in sand to allow it to cool slowly and evenly.
Thanks for the tips!
