I don't think that was the constructive answer the OP was hoping for........Rude72, please excuse him.
So, as you stated you a newbie and believe me even an experienced person may have a difficult time with the tedious task of adjusting doors and gaps. Make sure the hinges and pins are good and...
I agree with the silicone and metal sandwich gaskets, but the ones that came with the cast aluminum valve covers from Mopar Performance were great too. They were kinda thick black ones.
You should vent the crankcase and eliminate the possibility of any pressure. Also, most valve covers will have a baffle (or plate across the opening) where the holes are in the valve covers. Since yours are cast, there may be a place to screw a plate. A small plate made of sheet metal will suffice.