FYI - BIG difference between a "Real" 427 Cobra and an "Original" 427 Cobra. Shelby still makes 427 Cobras - take a look at
http://www.shelbyautos.com
The Shelby series 4000 cars that Shelby builds today are considered "Real" Shelby Cobras, but they aren't rare and weren't built in the 60s. So just because you see one with a license plate that says "Real", doesn't mean it's an original 60's Cobra.
As for telling the difference between an original and a replica, there are some that the only way you can tell is by the serial #. The Shelby 4000 series cars and the Cobra replicas built by
http://<a rel="nofollow" href="http:...m/home.cfm</a> are pretty much exact replicas of the originals, with some improvements.
I've gone to several Shelby American Automotive Club (SAAC) shows, and I have seen several original 289 streetcars, but I have never actually seen an original 427 Cobra (street or S/C).
Pete