Thank-you all for your sugestions.
Since I got some time in my schedule I will be taking the manifold off this weekend; unless I go fishing..
Yes, I agree with joelittel; I'm not going to get metal shavings in the oil.
If the threads look pretty OK I will use a sealant, hopefully nothing more than lok-tight. I have a bottle of high temp thread sealant that I got many years ago but the that stuff is getting pretty thick and I'm not sure I can find it anymore.
I will let you all know what I determine for the stud.
The exhaust manifold will be off! I will sand-blast it and apply Eastwood inside and out ceramic paint.

Maybe less heat in the engine bay will let you know
