I used the Aviation just on the water passage area at the front and rear ends of the gasket to keep it in place when dropping the intake down so the gaskets don't move around. Use the Ultra Grey for the china walls, go 1/2" up the gasket. Before so doing make sure the thread holes in the cyl heads and the bolt threads are clean, so you get accurate torque readings.
BTW this may be obvious but: some gaskets have the front water passage area open and the rear one closed, this is because the cyl heads are the same casting and the gasket is the same too, just reversed from one side to the other. This is because there is flow only at the front of the intake, not at the rear, the hot water flows from the block, into the heads, then forward to the head to intake passage. Make sure that if you have this type of gasket that the closed ends go toward the rear of the cyl heads and the open ends go toward the front or else the engine will overheat quickly because the hot water can't escape. It sounds ridiculous but don't laugh it happened to someone on here whos engine was rebuilt by some 'professional'. LOL!
I used the Fel/Pro marine gaskets for this engine (Pre-Vortec like yours) and they sealed fine.
