Valve cover gasket opinion...Cork vs Rubber

[QUOTE="Michael Brisebois]I always seem to have seen to have difficulty getting my valve covers to seal well on my 273. What do you guys like...and do you use gasket sealer?[/QUOTE]

As weird as this sounds, the 3'rd 'short fuse' 273 (built
circa '79) leaked from the right rear and left center !!!
--- Light Bulb ---
File down the head to cover surfaces...

Michael Brisebois
I look forward to Your Pictures.