Look you agree the LO and BO cars had a VIN right? Those were 383 cars shipped to hurst campbell and they have correct VIN's. SO Ma Mopar stamped the tags like they wanted them and attached them to the dash.
Now on the first Dart GTS, I heard the same Ma Mopar wanted the Barracuda to be the hot car and so did not intend to build a BB dart. They would not have needed Mr Norm to "shoe-horn" a BB into a Dart! Hell they knew it was an A body, They are the same! They just decided late in the production run to do them. Using all the barracuda BB parts. Why? beats me.
So the Mr Norm car was a backyard BB. Does that make it the first BB A Body? Not by VIN.