Yeah stainless can be used to shim the head to change CR ratio but a sealant is still needed - where as copper it seals on its own once annealed.

Surely in today's day and age there must be a sealant where you apply it to the block and the head (once they are machined nice and flat) and all you have to do is bolt it together with out gaskets etc. Is there anything else than loctite 515 (its not high enough temp I think)?