Not sure what you have tried already but here is what I do. I'm guessing that the leak is between the valve cover and the head. Making sure both mating surfaces are clean and flat, use a good rubber gasket, put sealant on the top, between the gasket and the valve cover. Don't put it on the bottom so it can be removed later if needed. I have always liked copper coat in the can (not the spray). Prior to attaching the gasket, make sure the valve cover lip is flat and straight. For the bolts, use hold downs so it spreads the load. Do not over-tighten. Just snug will be good enough.
A few years ago, I had an issue with older steel valve covers sealing. Instead of a gasket, I used about 1/4" silicone, let it set for about 30 minutes then bolted the cover down without much torque so it didn't squeeze out the silicone. The permatex black works good for this. Worked great but taking the valve covers off after that was a real pain. Also it looked a little messy, but it did seal.
If they aren't damaged, the Edelbrock gaskets you already have should work, but do a good visual inspection to make sure they are in good shape.
Good Luck...
