Billet Gas Cap For '66 Stang

I think the bare cap is to plain. But the Ford emblem doesn't match the rest of the back of your car. Maybe a different emblem or version. Maybe have somebody machine something into it.
 
I don't care for the emblem either. It takes away from the billet. Get some ideas of what you want and take it to an engraving shop. They can engrave a pic or lettering on a small round disc that you could glue on that.