Great question thundercock, and there's two ways to look at it I think, you could argue that Marciano would be much bigger if around in today's era. With modern weight training and diet it's reasonable that he might pack on more muscle and be a 205lb brick shythouse, then you gotta factor in today's PED's. these things can turn you from a featherweight spastic who gets smashed by the likes of morales, to a raging welterweight with a huge head who KO's light middleweights.

If Marciano was using today's PED's, weight training and eating the right diet like most these guys, then he'd be a legit heavyweight powerhouse who'd probably be owning today's division.

Or you could say he'd go the chavez jr route, diet and diuretic down like hell and manipulate the weigh ins so that he can blow up overnight and kick the shyt outa muthafuckas half his size just for laughs. in which case it's definately possible he could be challenging the big super middles and light heavies!

He'd definitely be light-heavyweight. Sure he could easily be at cruiserweight, but he'd be too short, as cruisers stand no shorter than 6'.

He would fight at cruiserweight. 175-200.

He'd be Cruiserweight.

He'd be a light heavy for sure.

ROCCCKYY FIGHT AT PENISWEIGHT! IT BEST WEIGHT!

marciano fought between 180/190 pounds so today with day before weigh ins what weight class would he fight in ,there's no way he would be a heavy weight or even a cruiser weight he could do light heavy without any problems most fighters put on 10 ponds after the weigh in so the weight wouldn't be a problem , 168 might be a bit to far but he could do it joe calzaghe would be 200 pounds every time he started training for a fight around the same as the rock before training .

it seems strange to me that marciano would be fighting the likes of froch ,ward ,hopkins,cloud today not the klitschko's or even david haye.