Are you coming to this conclusion based on the fact that he easily handled Jimmy Thunder ? (For those who don't know Jimmy Thunder's style was very similar to that of Rocky Marciano)
More the fact that Marciano had trouble with slippery guys and Byrd was much faster than anyone he fought, plus Byrd could take body shots very well, which is why I don't see Rocky doing enough damage
I'd take the Rock by stoppage. Though Byrd has survived against bigger puncher and stronger men... Really a toss-up if you ask me..
Marciano was a lightheavy by today's standard. I would favour him slightly, and he was a much greater fighter than Byrd, but those were different times.
This is actually a decent style clash... but how can you not pick Marciano? But over 12 it could be dicey. Byrd would win some rounds.
Marciano....Byrd will experience punishment like never before..career ending fight..IMO...Byrd defense will keep his face safe for a few rounds, but his body/arms/back every other part of his body will be punished.