Tuning with jets, Power valves and an O2 guage

Here's a trick... Get all the oil and grease (including oil from your skin) and take 3M yelow weatherstrip adhesive and glue the gasket to the cover. I used the same stock cork gaskets on my old 440 from 1995-2003. Checked the valves 3 times a summer and they never leaked. Did it when I was a mechanic, they never leaked or moved and as long as you don't overtorque you're golden.