What’s the best sealant to seal the shims and cylinders to the case?

Curel T is what I used.

I am stuck in dark ages and use Permatex Aviation sealer.

I like the Permatex Aviation too, used it to seal the case but I think I’ll try the Curil T2 for the cylinders and shims.

Was/is everything in the dark ages dark?
Also, my choice for many locations

I used Permatex Copper. From cylinders, to heat exchangers, to Harley exhaust, it hasn't let me down.

That rather expensive orange stuff, and I forget the name. Ford engine lube is real good smelly stuff for bearings, but don't get it on the cylinders.