Maybe Michael Spinks Definitely Leon Spinks Possible ken Norton ,50 /50 on that. Hashim Rahman maybe Trevor Berbick Michael Moorer
Basically he would have a chance against anybody with a less than stellar chin, however good they were otherwise.
Probably some guys that moved up from light heavy and cruiser and only found average success at heavy, guys like Al ice Cole, Bob Foster, Jirov. On the high end he could land a bomb and maybe turn the trick on Moorer after being outboxed. Baer had a great chin and a big punch but his size which was an asset in the 20s and 30s would be nullified by most heavies by 1970. His lack of skill would be badly exposed without the size difference.