Yes...the "LO" and "BO" cars were Chrysler-sanctioned "Race-Only" 1968 cars, and were shipped , by Chrysler, with the VIN of their ultimately -installed engine. This was not the case with Mr. Norm. HE decided which 1968 cars were to be converted and sold at his dealership. Chrysler would not have known which cars were converted, so they could not supply a tag with an "M" engine code on it.
As far as the 1st Dart GTS, I agree with you...Ma Mopar didn't need Norm to show'em how to build a BB Dart.