We have been using Cometic multi layer head gaskets for ten years now with no problems on a 16.6 compression NA alky burner, 10,000 rpm SBC JrFueler. running water in block/heads with no leaks.
But we do use solid copper head gaskets in the early iron JF Hemi, at Gene Adams suggestion, but no water. But we do have to add some sealer around the water holes, because when we smoke tested it to look for better vacuum, it was leaking thru the water holes. When we smoked it it was confusing when we had a colum of smoke coming out of a zoomie stud hole that is in a water jacket.
One neat option Cometic offers is I have sent them my trimed intake gasket, and they will make a patern and a part number to order.
Cheers, Jon