For assembly I use
GM assembly lube, you can get it at any GM dealer shop off the shelf. It can be used inside the cylenders and spread liberaly on everything else. There is also the cam assembly lube, it's a bit thicker to keep it from being wiped right off, but not absolutely needed with the lower spring pressures in our old engines.
As far as sealants, I'm partial to Gunk Aviation Form-a-gasket for most surfaces, I've had pretty good luck wit it overall. Still, making sure you have good clean and flat surfaces for your gasket makes all the difference.
Not a fan of silicone anything on engines, I always find it squeezed out internaly & it ends up inside water passages & oil galleries.
