As much as I love yesteryear's NBA, solely based on math it's hard to argue that recent GSW teams wouldn't beat every other team in league history. The modern NBA is effectively a three-point contest. GSW averaging 12 threes against other all-time great teams who either didn't shoot the three or made significantly fewer threes would be a nearly insurmountable advantage.
We're in a time where the league average is 12 3PM per game. That's the entire league, not the top teams. Putting a team like GSW in a time machine against teams who averaged fewer than 2 ('86 Boston) would be such a huge edge.
The biggest question in any all-time hypothetical is which rules are they playing under? Old illegal defense and hand-checking? Or modern rules with zone defense where you can't touch anyone?
It'd be a blast to see the '96 Bulls against '18 GSW under the old rules. Let Pippen and MJ be physical. Pippen vs KD. MJ on Klay. Harper using his length and hand-checking Steph all over the court. Rodman vs Draymond. '96 Chicago would probably translate better than any other older team because A) they had the GOAT B) they didn't heavily rely on the center position. It'd be great to see KD in the old rules too, isolating at will against smaller defenders. As great as Pippen was, how effective would he be against a 7-foot scoring machine like KD?