Francis

I think two gaskets between the head & manifolds could cause you more problems than they solved.

When I machined my mine (they had already been done once or twice in their history) I had to machine some of the excess length off the pilot rings to allow the manifolds to pull up tight onto the head. This worked fine.

For memory I didn't need to machine the heat box faces. Two gaskets there would probably be OK if they were wide enough to pull together without squashing out of position.

Ken