There's a sneaky trick to minimize valve cover leaks. Stovebolt cylinder heads are flat where the gasket sits, so oil can puddle behind the gasket and seep underneath, unless the gasket is glued down to the head. It's also necessary to assure that the valve cover flange is completely flat- - - - -overtightening the 4 bolts that hold it down can dimple the sheet metal and result in uneven clamping along long sections of the gasket. I like to use weatherstrip adhesive to glue the gasket to the head, and a thin layer of grease on top to allow the valve cover to be removed periodically for valve adjustments without damaging the gasket. Gluing the gasket to the head builds a dam to discourage seep leaks.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!