360 intake manifold gaskets?

CLEAN the surfaces with acetone, paint thinner, other DRY solvent make ABSOLUTELY SURE the surfaces are CLEAN, oil free, and dry

Put a nice big bead, I'd guess about 3/8. THEN after you tighten down the manifold, examine the front / rear carefully. If there is some "sticking out" take your finger/ towel and smooth it "into" the gap. If none is sticking out, and there is ANY doubt that you have contacted and compressed the bead, ADD some out to the outside of the gap, and then, as above, "form" the bead.

I don't build very many engines, anymore. Back when RTV first came out, I built about 10 between my friends and I and NOT ONE leaked a drop.