I have been doing so searching, it appears that this is a very common problem. Back driver side on mine is leaking. I was using rubber coated cork.
From the searching it appears that Mr Gasket Ultras might be the ticket? Anything better these days?
I am going to make sure they are not hitting on anything (383 with 906 heads and RPM intake). But I don't think they are. They rock on the head without a gasket.
