I'll mention a quick easy tip for you guys for annealing. You can use a gas stove or a electric stove.
Set a new copper head gasket right on the burner, leave it there till you see all the colors of the rainbow start appearing, then leave it for a few seconds longer.
Then shut stove off & let cool.
If reusing a copper head gasket, scratch it up with a 3m scotch brite pad, soo you can see the colors re appear as annealing.