Permatex sells the round circular block gasket by itself & it is a slight bit thicker than the one that comes in the 3 piece MP kit. Make sure the block recess is clean ed with a bristle brush & the gasket stays in place as you lift the adapter up into place & use sealer. On the other leak I'd check the surfaces of the underside of the bolt head & the snout of the adapter & there's a gasket that looks sorta metallic like ex manifold gaskets that reportedly seals pretty good with sealer, dont remember what brand it is but you might be able to cut a piece out of a header gasket. Good visual as there's a reason (as you know) for it to keep leaking like it is. EDIT found it, FelPro # 70522