I'd take Monzon by late stoppage. I think Nunn looks good early on, but takes damage each round and slowly wears down past the 6th when the tide turns in Monzon's favour. I might not be the best person to answer this, but that's my impression.
The above talented poster I believe has it right. Michael Nunn, who was very talented and had good speed would make it very competitive early on, good boxing ability but then as previously posted, Carlos Monzon's tenacity, hard left jab and countering rights begins to turn the tide around round in round 7 as the slow footed Monzon begins to cut the ring off on Nunn, forcing exchanges, Monzon had amazing stamina. By round 10, Monzon's hard right hand begins to find it's mark, and during an exchange in round 12, a crisp right hand followed by a two punch combination deposits Nunn to the canvas. Michael arises, only to be met with a smashing right hand that is set up by a stiff left jab. Nunn staggers back defenseless unable to defend himself, the referee intervenes to end matters by a TKO 12 victory by Carlos Monzon.
Nunn was a very smart fighter but monzon was on another level. Nunn would have to fight out of his skin and most importantly, not decided to take full minutes of the round off and try to please the crowd by fighting on the inside. The south paw aspect would be interesting too. I can see it being close up to the mid rounds, were Carlos starts to pull away ending up give nunn a bad beating on route to a UD.
Nunn's speed and angles are all wrong for Monzon. He will have Carlos looking slow, ponderous and a step behind. However, Carlos' consistent jab, efficient feet and small adjustments and most importantly, the timing will start to narrow the gap. By rounds 7 - 9, Carlos is finding success with the jab and half-stepping to his right to throw the right hand. Nunn was great on his day, but I don't trust his whiskers, his workrate and his understanding of controlling the fight to trump what Monzon does best. Carlos will hit him to the body and hurt him on the inside exchanges, and just like Toney did, he will catch him with the straight right and also the occasional overhand right. I think Monzon would stop Nunn or have either the ref or the corner saving Nunn from more punishment. If Nunn sees the final bell, then he could feasibly win on points for the flashier looking work, but he will be roughed up to do so - roughed up quite a bit.
