I have been using these carbs since the early 70's.
I was told back then and believe they were originally developed to replace the vacuum operated big block tri power corvette carbs which were introduced in I believe 1967. This I always believed to be true due to the L side fuel inlets.
Somewhere, someone figured out these would also bolt onto the mopar six pack manifolds with the only issues being the L side fuel inlets which many worked around employing different approaches.
Hustle stuff/ Direct connection jumped on the bandwagon and began offering the carbs for both big and small block applications.
IF the carbs had been developed strictly for Mopars I believe the fuel inlets could have easily, and would have been put on the other side.
I also believe that someone at holley looked at the earlier Ford tri power carbs that had been around since 62 or so and said with some minor mod's we can adapt these over to the corvette and the 4782 / 4783 series was born / introduced. Along came the 69-1/2 cars followed by the T/A & AAR's and as mentioned above someone bolted them on a Mopar. So, we sit here almost 60 years later disputing the original intent for the carbs with no one really knowing the actual facts.