[69a]

I've been using Hylomar Blue for 30 years, which I think is equivalent to the non-hardening Permatex. On flathead pan gaskets I just put a thin continuous bead on the block, I don't spread it out. I then put the gasket on and press down to flatten it out a bit, then put another thin bead on the other side of the gasket, and fit the pan. Gently and evenly tighten up. Don't over tighten it. Hylomar Blue is great when you disassemble too. It remains sticky, you can remove the gasket easily with a scraper. But you have to use a solvent to get the last of the sealant off.
I use grease on inlet manifold gasket, both sides.
I haven't heard the word Shellac for over 50 years, but I was taught to use Shellac on OHV tappet covers. Put Shellac (any sealant would work) on the top side of the gasket then fit the gasket into the cover. Put grease on the bottom side. You can take the tappet covers on and off without damaging the gasket. Just put a little grease on every time you refit it and it will last forever.