Bob,

Here is my recipe. Clean the cover and flange very well. Set the flange on a bench corner and hammer the screw hole dimples flat as well as flange.

Apply your favorite spray gasket adhesive to the flange AND one side of the cork gasket. Let them dry and stick them together.

I have always put sealer on both sides, but the general consensus seems to be that the side towards the engine is fine as is.

Clean the head mating surface well and install the valve cover. As I read over your post I see it's a 216 so you have no screw holes to hammer the dimples out of...my bad!

When you cinch the two bolts down, do it with much reservation. They only need to be snug. Too tight and the valve cover get sprung and could leak.

Making sure the flange is clean and flat is the key. Although there is a cork gasket involved, this could almost be looked at as a mechanical seal. Good luck.

Stuart