The only hope for Marciano would be surviving to the later rounds and turning it around. Tyson lost himself when wading into deep waters, and was much more prone to being caught and hurt. If it's a championship 15, Marciano could turn it around in the 13th or 14th, as Tyson usually would start to slow in the 10th, and I'd like to bet that Marciano would be able to make it with his oddly mechanical way of defense, but who knows.
He doesn't have the stamina of the rock. That's his one disadvantage here. By mid-fight, his power will be waning and the rock's won't. Of course, he might well end it early. Setting out to win a fight with Tyson by standing toe to toe with him is rough, and that's basically all Marciano could do.
Marciano would stand a better chance ( Not win mind you ) against prime Ali or Joe Louis than prime Mike Tyson. Tyson would be better athletically, better skilled, better power, taller and bigger, and more aggressive . Marciano would have a better chance than I would but that's not saying much.
Not sure, but I can see both men hitting the canvas. I think it would be up to the man who scrapes himself off the canvas and desires to win above anything else.
The fight wouldn't go past 4 rounds. Mike would be in heaven finally fighting a HW with a shorter reach than his but much slower all around.
Berbick and Biggs had a weakness to big punchers, and so did Williams, but I believe that The Truth might be able to keep him away for most of the match, and has the sort of heart that'd give him the chance to get up at least twice, so he's got a decent chance there to live to see a decision. Not that he'd win one.
Marciano was the superior inside fighter and they were just about the same height, they would spend the whole fight in Rocky's wheelhouse, on his terms (as Tyson didn't really fight going backwards). If Tyson doesn't take him out in the first 6-7 rounds he's in for a rough fight. Tyson was accustomed to fighting taller guys, fighting a guy who would crouch even lower than him would be awkward.