Rocky Marciano vs Oscar Bonavena

Take Rocky give him 6 inches in reach 20 lbs of muscle 1/2 inch height and slightly tougher skin and you ve turned him into approximately Oscar.
Maybe Bonavena bum rushes him and the weight and strength advantage is too much physically for the 185 lbs Rocky to overcome and its over in a round or 2. I rather think Rocky is tough and cagey enough to survive to a late round or the distance but is just too small to deal with Oscar and loses a late tko or lopsided decision being decked multiple times.