There had to be a reason why originally the small block coil wires were org/blk and big blocks gry/blk like you have mentioned but perhaps it was just over engineering by Chrysler at the time for whatever reason. And with the aftermarket maybe the engineers saw a way to wire them to work on both? Just a wild guess, no clue, but what I have has worked as it should on quite a few older SB Mopars.
