Well let's see the pictures then shall we? Because the AMD replacement panels are identical for the inner and outer wheelhouses. Same part #, same part. All the '67-69 Barracuda's, all the Demons and Dart Sports, all the Dusters.
I replicated your 14" measurement, the raised lip on the outside of the quarter doesn't change a thing for the tire clearance. The lip on the wheel house is what matters, so let's see that measurement. The frame rails are in the same place, so, if the inner and outer wheelhouses are the same part (and they are), then you're not going to get a measurement that's different by more than body tolerances.
Maybe @AJ/FormS has a picture of the measurement on his car, since I already made reference to his 13.25" distance from inner to outer wheelhouse, which is the same as on my Duster.