I say skip the gaskets and run one of the multiple "phenolic" spacers that have popped up recently. Aluminum is a fantastic conductor of heat, and a spacer will prevent your manifold from becoming a big heat sink for the cylinder head.
You'd still need gaskets, no? One side has the gasket grooves, it mates to the head. The other side is flat and would need sealed.
guys the higher temp rated gaskets don't seem to be holding up either.. i got a handful of pulls and one dyno run in before the gaskets let go.. ordered a phenolic spacer today.. just an fyi.
Where can I get this?Viton -225 O rings worked for me. Rated to 400*