I'm with Larry. I think he bust Rocky up with his jab. Larry has a huge size, speed and most importantly skill advantage.
Marciano stops Holmes late. Larry was always wide open for the overhand right and no one had a better one than Rocky.
I'll take Larry to box the much smaller Marciano like he did Leon Spinks. Either late tko on cuts and battering or Rocky straggles to the final bell.
Marciano knocks him out. Holmes will get worn down but he won’t be let off the hook by lesser skilled fighters like Shavers or limited fighters like Norton. He will get tired from the relentless body pounding, stamina. and ring generalship of Marciano. The big right connects eventually but there are few better finishers then Marciano. Larry can’t escape the assault and falls in 11-15 area.
I consider Larry Holmes as the 3rd greatest heavyweight after Ali and Louis. He would defeat Rocky by decision after a tremendous battle. Larry’s jab would trouble Marciano but Rocky would still manage to get inside at times and rattle Holmes. But the Easton Assassin was the superior ring general and would defeat a bloodied but unbowed Marciano.