360-383 A-debate...max builds need not apply.

Ok, a little closer to the topic. The '71 Roar Runner base engine was a 383 4BBL, and the 340 4BBl was an extra cost option.

https://www.hamtramck-historical.com/images/dealerships/DealershipDataBook/1971/71_Satellite_31.jpg

Not provided as definitive proof of anything. Just a talking point.