I'm in the middle of the same job again (different car this time) and I've run into something my old Lumina didn't have a problem with. There is pitting on the manifold and it is pretty deep. The heads have it too but it is less severe. You mentioned JB weld but I don't have any. Would blue RTV fill the pitting and seal the mating surfaces or should I pick up the JB next time I'm out?