Sealing Stamped Small Block Valve Covers – Grrr

I went through similar problems as you. Are you using thread sealant on the cover bolts? That solved leaks I had on both the lower firewall bolts on each cover. I then used a lot of Gasgacinch on both sides of the cork gaskets. Sounds like your using something similar with 3M. Also found it was weeping out along the cork tabs that place/hold the gasket in the cover. So covered the exposed cork tabs with snot (it dries almost clear so it’s not noticeable). I tried the steel core rubber gaskets (Mopar Performance ones) but still had several leaks so they are hanging up in my garage. I suppose if I did the same tricks with snot and thread sealant on the MP gaskets they might not leak now?