1951 Joe Louis vs these guys as they were in the late 60s/early-mid 70s. Not necessarily at their best unless their best happens to overlap with the time frame. How does an aged Joe Louis do against these guys one on one? By further extension how would that version of Louis do in that era? Say 1942-1951 Joe Louis against these guys from 67-76 had he been active during those years? Oscar Bonavena Jimmy Young Jimmy Ellis Jerry Quarry Leotis Martin Chuck Wepner Mac Foster Floyd Patterson Joe Bugner Ron Lyle Throw in any other contenders that you think would smash Louis or that Louis would beat soundly that aren't on the list.
If this is about the Ghost of Joe Louis (37 years of age), he´d probably retire if he met the wrong guys on this list first.