Mildenberger was promoted as an soccer player, but he was actually an accomplished Lefthanded EU Hvy. Other than SRRobinson's one title fight with a lefty, the boxing landscape was bereft of quality Left fighters because trainers would convert them to Rightys so they could make fights since MGRs didn't want their fighters to look bad vs Leftys.
Texas with it's new Astrodome offered him a venue whereupon he moved and bought a home in Houston where his mangled Bio Fantasy was produced that I may have been a part of in a public setting. Strictly cornball stuff then sorta like now.
Anyway, Ali looked bad vs Mildenberger who got on top of him that had Howie Cosell choking on his toupee before an Ali combo saved the day.
Any other Lefty Hvy Contenders before that? I reckon right around the 2000s Leftys in all weight divisions started appearing, the best ever being Manny Pacquiao. I know Lewie fought one and looked like doodoo...