Johnson was a very good fighter who was good enough to win titles in essentially two eras of Light Heavyweights. But Archie would have had to much craft for him and would have ran Johnson into something big and stopped him in the middle rounds.
Marvin had problems taking it to the body, and his stamina deficit when faced with resistant opposition is well documented. Archie certainly had the punch to dispatch Marvin with a single shot, but like his student Mustafa Muhammad, I think he'd more likely lay back, let his man expend himself a bit, then pick apart Marvin for a late knockout win.
Archie probably would lay out Marvin by the eleventh round, but Marvin would take an early lead on Archie, before the latter asserted himself.
