Could have been the 90s or even 50s - Marciano,Charles,Walcott,Patterson etc. Not nitpicking but I would say 1970-75 instead of'76 was the REAL golden age OF the golden age. After '75 Ali,Foreman and Frazier were never quite the same. The only one of that elite group who'd maintained his peak was Ken Norton.
I was about to make it 70-75, but I felt I should include the 76 Ali-Norton fight. That was the last of Ali's big rivalry fights, and the last of the top 4 from that era fighting eachother.
Up to the end of that decade Rocky would surely have been all time top 5. He's since been well eclipsed but that's another story. Walcott,Charles and Patterson were no mugs either.
I see what you mean but Muhammad had fallen quite considerably from what we consider to be his 1970s best form which,imo,was circa 1972-74. 1975 was the last trace of it seen in Manila.
I'll probably get slated, but early thirties to the early 40s is a era I rate highly. Maybe not 2nd but at least we had the best fighting the best