I think Marciano could win it. As people say, it's a matter of styles. I dont think Tyson's style would do well against shorter fighters of Marciano's ilk. I've written about this several times before. I think Rocky could crowd him, stay low, keep his head pressed in Tyson's chest, make it messy and ugly. Tyson's feet were too square-on on the inside and he gives away most of his natural strength with the deficiency in his inside stance. And just because marciano's only 185 pounds let's not assume he cant take a fair bit of punishment from Tyson. Marciano was a beast, a very determined beast. Blah, blah, blah ..... we can analyse all day long. It proves nothing. Most of you say "Tyson. Too big. Too quick.", and I give reasons why that's not necessarily the be all and end all. Marciano was an awkward stubborn ******* of a proposition. He might run into a few dynamite punches from Mike but it's equally true that he's bound to find Tyson with some monstrous blows of his own too. It's no foregone conclusion.