Sealing Stamped Small Block Valve Covers – Grrr

So I should hammer down the bolt mounting surface closer to the rails?
Yes.
They should be flush with the rest of the rail and straight all of the way down.
I will NEVER use cork gaskets again, i only use the neoprene (rubber) ones and use Gasgacinch on them.
Another note is to clean the rails and head surfaces so they are absolutely clean of any gasket material and oil.