To save the stud head threads (especially the back one), make sure you cut the webs on the exhaust manifold, and have the manifold surfaced flat on the head side gasket face. Cutting the webs is cutting the gasket face of the casting so that each exhaust runner and it's two bolt holes are isolated from it's neighbor(s). I suggest a Sawzall and about three short metal cutting blades, or a good whiz wheel. This is a very necessary mod on turbo manifolds, and a good mod on carby mani's. Also helps prevent manifold cracking from heat cycling stresses, esp. on the turbo.

If you have access to a non-wife controlled oven, also try heat baking the mani at 500-600F for about 12hrs, then let it cool slow (leave the oven closed until cool). This will relieve stresses in the used manifold. Have it surfaced afterwards, as most will move a lot as they relax. If you have a wife, and you use her oven for this, you're on your own, and I won't send flowers....