I think it was on the PY site where a guy used a silver ceramic type paint that went to 1000 degs. he put that on the exhaust ports and then painted the whole engine with the Hirch paint. Looked pretty good many years latter the silver kinda blended into the blue instead of the rust. Just no way to keep the pontiac paint from burning off the exhaust.

I would also make sure you have degreased everything you can and use a hardner with the paint and a paint gun. I wish I had done this last time.