/6 head

That's what I mean - your motor has fresh surfaces on both sides of the gasket. If you try that same gasket on an old crusty block you might have trouble getting it to seal.

And there are a bunch of composite gaskets - felpro, corteco, victor reinz, various australian ones (permaseal) etc...

as long as its flat clean it really well and if you like use a red scotchbright disc on it...