Head gasket sets?
You listed the primary seals/gaskets required. The local autoparts stores usually carry an intake manifold gasket set, which includes a bunch of what you need (intake, TB, EGR pipe iirc, etc). You'll probably want to replace the 4 rubber washers for the steam pipes on the back of the cylinder heads, as they usually tear up -- pretty sure these will need to be ordered from GM.
While you're in there, you might consider some other things. You have the option of installing thinner compressed thickness head gaskets, which will net you some increased compression. You might also consider having some portwork done at this time.
Anyway, just tossing out some thoughts...

