Well there have been none documented or found to date. And think of how much research has gone into every possible Mopar built. There are tons of very high dollar collectors out there looking for these one offs. While they do strike paydirt every now and again, it is usually a dead end. Some documentation would have existed and the speculation and searching for the car(s) would have been in the magazines for years. They didn't make any 1970 Daytonas and look at the commotion they cause.
And the hemi was a low volume production, unlike the 440 six pack. And look at how very few actual 1972 440 6 pack cars are known.
While you never say never with Mopar, the possibilities are less than 100th of 1%. But, if it could be documented (and if this guy honestly believes it, Galen would decode it for free I'm sure) he would be sitting on the most valuable Mopar ever. Forget the 7 1971 converts - this would be it.
Not too likely huh?