In my service manual, it is called a cylinder head cover, but they also call the valve covers a cylinder head cover. It is just for keeping the alignment of the plug boot straight over the spark plug. The part could be sand blasted and then powder coated to look really nice, well what little you can see of it anyway. It seems that there is some sort of covering on that part and it peels off over time and with the heat. I have never seen one in a gasket set, but I have yet to find the 2 donut seals that go between the exhaust manifold and the double down pipe for my N/A. I get the big one that goes on the cat converter, I had always wondered what that one was for until I replaced my converter and saw the gasket there.
Oh well...........
Russ