/6 rebuild advice

What's your thoughts on those "real" gaskets?
I have them in mine as well but haven't run my engine in quite a while so the oil sits in the sump below gasket level. I've heard nothing but bad news about their gaskets, a good idea on paper but not in practice...
I bought 2 of each when I bought them to have spares ..

Also on the talk of K seal above I've never seen anything but the metal ring type head gasket on any /6... No plastic rings
I don't think that "technology" was out yet when this engine was in production