I think those Celtics teams would win « if everything was equal ». I am talking about « as is ». If you think athletes of the 60s have any chance at all vs the steroid / HGH freaks of today, we’ll need to agree to disagree. I was referring to a recent champ (2019 raptors that I happened to watch a lot), not the worst team of today. And yes, I think the 2019 raptors would sweep the 60s Celtics and make them look silly.
(Again : if those 60s players had the nutritional and steroidal and medical and coaching advantages of the present - you are right. You only need to watch that footage of Ruth and Gehrig whiffing like school boys to see that HoFer is relative to the era…)