Welcome to the forum!
If the owner says it was in a light wreck, I'd definitely be paying the money to see what came up on that carfax. In all honesty, it sounds a bit sketchy to me, and you have to remember that it probably was driven hard and may have more problems than meet the eye. If it's in your price range, I'd look at an 03-04 because the 99's were underrated in HP and had some problems with them which you can probably find through google, as I don't know all the specifics on that. Those issues may have been fixed by the owner though. The terminator cobras are plentiful because people are looking into GT500s.
If you have any other cobra questions, I'd check in with the Special Stangs/SVT section-- they can help you out also.