Under the Bareknuckle rules wrestling , choking with forearm , head butts were allowed and Sullivan to prepare for his fight with Killrain brought in World Wrestling Champion William Muldoon to work on grappling. So if Rocky fought Sullivan under bareknuckle then Sullivan however if Rocky had time to acclimatize like a boxer would have for fighting a MMA fighter then Rocky would have a better chance.
The gloved fighter would need to harden his hands as the bare knuckle guys did.....tend to go with Sullivan in this match...with gloves and no throws...Marciano
With gloves.. No doubt s its marciano. From what information I've picked up on regarding sullivan he was a tough sob, but I lean towards marciano by late round ko.