I got 14-1/16" on my '74 Duster and 14" on my '71 Dart.
It should be the same measurement on all 67-76 A-bodies. I'm 100% on the Dart's, Duster's, Demon's, Scamp's, Valiant's, and Dart Sport's. Not absolutely positive about the Barracuda's, but it should be the same. Keep in mind that everything but the Barracuda's can swap the all the front end bodywork, that's how Duster's became Demon's and Dart's became Scamp's etc...
I'd guess that it's supposed to be 14", and there's probably small variations based on assembly line tolerances and how people measure (tape measure, ruler, square, straight edge etc.)