Well, that looks like a valve cover decal. Not sure about different lettering, but you can get duplicates of them here: http://www.drcl***ic.com/catalog/Camaro/Decal/D00173.html
I dunno if its metal or not... I think its just a decal. 53sled, if I was to buy a repro and send it to you, could you do one with different lettering? I think they have a gold background.