My 37 Buick with a 263 straight eight is even more of a manifold headache than a straight six. Since we make LONG trips I probably had more trouble than others that didn't have the manifold hot for sixteen hours at a time. I welded, brazed, or stainless tigged several during the last 40 years and finally found a virgin replacement which gave me the incentive to try something different. After surfacing with the intake and exhaust bolted together I threw away the alignment rings and used studs to help align during installation. Finally I discarded the exhaust gaskets and used high heat (red) silicone. With this configuration I've had no leaks for the last fifteen years. One possible explanation is that it lets the manifold "creep" around between hot and cold cycles. I really don't care as long as it keeps the big sucker off the welding table.

[img]https://i.postimg.cc/VrNRhvNX/Pont-heater-Buick-sealant-003.jpg[/img]

Evan