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I'm about to reinstall my intake/exhaust manifold and the gaskets I have are those critters with the metal in between two layers of who knows what kind of compound. I've heard talk about using some high temp goop like ultra copper or the like on the gaskets. Anyone have any thoughts? Also it was suggested that I loosen the three bolts that hold the intake and exhaust together (with a new gasket of course) then after tightening down the manifold tighten the bolts. Again your thoughts.

Do not use sealant on manifold gaskets. Stop and think about it for a minute - the exhaust manifold gets much hotter than the engine block and thus expands to a greater length when hot than the block does; thus there is an ever-so-minute movement of the manifold against the gasket surfaces especially at the extreme ends as the engine heats up and cools down so a sealant is not appropriate. For this same reason torque of the manifold fasteners is important.

If you had the manifold surfaces, both intake and exhaust, surface planed as an assembled unit then you can bolt it directly to the block as as a unit. If you did not, then best practice is to loosen the hot box bolts, attach the manifolds, and then tighten the hot box bolts.

What is the recommended torque?

I'm not aware of torque specs for 1938 but given the engine similarity I'd use the spec for the post-war 288 engine, assuming the fasteners have the same thread size.

Which is?

If it is any help, here are the complete engine torque specs from the 46-50 manual. As O_D mentioned, if the bolt sizes are the same I would think the torque specs would be similar if not the same.

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Don't know offhand but that shop manual is on line here so you can look it up for yourself.