Marciano deliberately kept himself as lean as possible. He ran a hell of a lot, and was a wizard with the skipping rope. Apparently before fights he would even "eat" steak by chewing in, sucking out the juice and spitting the pulp out. I'm of the opinion that if he didn't do this he'd have weighed a lot more. Most HW's try to weigh as much as possible. He did not.
Marciano doesn't look "as lean as possible" on film when he's about 185. He looks like he could lose a few more pounds of water weight. Furthermore, Marciano had good stamina (though it's rather exaggerated by his fans), which is basically not possible if you enter the ring too dried out - clearly Marciano was not.
"Marciano was a health-nut. He ate "veggies," always carried a jar of honey to sweeten his coffee and chewed but never swallowed his steaks. He even had an exercise for his eye*****." http://espn.go.com/classic/s/marcianorockyadd.html "The Rock would chew each piece methodically over lunch, swallowing the bloody juice with slow relish, before he spat out the masticated pulp on his plate" In Black And White: The Untold Story Of Joe Louis And Jesse Owens Google. Use it.
Johnson won the title at 192lbs from a man who weighed 168lbs and was 5'7".Lewis was 230/245lbs and 6''5" spot the difference? Marciano's chances are all but zero because he was slow had rudimentary boxing skill ,poor balance ,no jab, a tiny reach and a tendency to cut. Louis had a great jab, one of the best of all time, fine boxing skill, excellent handspeed, blistering combinations, all time , power in both hands, good resistance to cuts,and he also had at least 7" of reach on Marciano. Johnson is one of the alltime greatest defensive heavyweights, great timing, balance, uncanny anticipation of incoming punches , with an excellent ability to block punches,and very strong . At 6'.25" He was 1.75"taller than Marciano. Neither Louis or Johnson were stylistically in the same building as Rocky and skillwise they are on a different planet!
No could Marciano's? Could Marciano's speed even be compared to Lewis's? We know his skills couldn't.
In the run up to his title challenge of Marciano, Charles lost to Harold Johnson177lbs, Nino Valdes ,and Rex Layne,yet he has guys like Bugner,Patterson,and Foster for breakfast? Yeah ,okatsch
Marciano scaled 178lbs for a fight in1948, he was 25 years old. In 1949 he weighed 180lbs for a fight, he was 26 years old. By heavyweight standards ,Marciano's torso was tiny he had a 39" chest.. His weight was centered in his thighs and calves, his reach was several inches shorter than his height.