If you want to see a lot of new wheels on a 67-8 Cougar or 71 convert. go here http://www.autowaretech.net/swonline/are.htm
Pick Mercury from the pull down and 67-8 Cougar from the next pull down and you can change things around to end up with something like this
Most if not all of the cougar vendors sell reproduction center caps. They have the blue cap with the running cat, the red with the mercury crest, and others. I prefer the blue with the running cat. You can try West Coast Classic Cougar, Cascade Classic Cougar, John's Classic cougars, Mustangs Unlimited, Autocrafters just to name a few that I know carry these. When I got mine they were $32.00 each.