I did some searching here on the Hot Rodders site a while back looking for header gasket recommendations and found this thread: how do you pick header gaskets for SBC
That lead my to use stock manifold gaskets on my headers. If you are running stock heads, with stock port configurations, they work just fine right out of the box.
Not sure though how they will work with the fuels you are using.
Here's the gasket set P/N's I ended up using: