I like James Toney because of his chin and defense. Not claiming he’d win but he’s got some tools that he could use in that fight
I am going with Toney, based on his proven durability against punchers, and his outstanding performance against Vassiliy Jirov. This makes him the least unlikely of the above men to beat Marciano in my eyes.
Considering how much trouble Archie Moore gave Marciano (and considering it's pretty well proven that Toney can run with the big boys and take their shots), I think Toney's the pretty obvious answer. Tricky style to deal with, countering the right hand is his bread and butter and Marciano's favourite punch, isn't really forced to punch down that much since he's the same size as Marciano so the benefits of the crouch aren't all there anymore, knows how to work on the inside, and has respectable power and kept up with Jirov's insane workrate. The more I think about it actually, the better a chance Toney might just have.