I have used Fel Pro intake - exhaust gaskets on slants with the stock intake, Clifford intake, Dutra exhaust and Hooker headers and never had an issue. Just make sure the mounting surfaces are clean and flat.
A week a go Rock Auto had one of their manufactures close our sales on the Fel Pro slant six manifold gaskets. It may still be going on. IIRC the gaskets were less than $5.00 each. I bought four of them.
