Best (and only) way to permanently resolve your valve cover gasket leak problems is to get an aluminum aftermarket valve cover. Clifford or Offenhauser makes them. Mercury Marine also made them for the 250/292s for their older 70s mercruiser boat engines. They're taller than stock covers and can be found on Ebay often much cheaper than the Offy or Clifford. I've picked up a couple extra myself.
-magic mike-
