You obviously missed the Ali Shavers fight. Who hit harder Forman or Shavers? You obviously don't know since you didn't even mention him. Not many people could come back after being hit by him but Ali did. Ali had a chin at least the one in this reality did.
Holyfield destroyed Tyson and I don't think Ali would have had much of a problem.
There is a reason why i mentioned Foreman only, because he was the only legit "HEAVYWEIGHT" puncher Ali's fought, by statistics and records... Still, Foreman build a part of his early ko-record over lhw, cruisers and small heavyweights, he's not in the league of modern punchers like Wladimir Klitschko (who has the best ko-record and is pretty much the hardest hitter in the division's history), Lennox Lewis, Vitali Klitschko, Mike Tyson and such, but is the only one comparable from past eras...
Earnie Shavers was absurdly overrated, all you have to do is check his bummy record, a cherry-picker with countless tomato-cans and guys under 200lbs or barely over it, that's how his ko-record was built... Decent at first glance, but for the most part completely irrelevant to modern standards, when compared to 90s heavyweights and modern super-heavyweights... So no, Shavers was nowhere near Tyson as a puncher, and George Foreman is the only ko-king of the 70s...
Also no again, Frazier, Norton or Lyle were not big punchers by today's standards, neither was Liston... If Tyson fought in the 70s he would've been the undisputed, undefeated king for as long as he wanted...