Benvenutti easily by late round TKO. De la hoya has not performed well in the couple of fights he has ventured up to the MW division. Nino was a great MW too not just a good one. I think he is underrated today because of his one-sided loses to Monzon. Monzon was perhaps the greatest MW of all-time so Benvenutti should not have those fights held against him.
Nino decks him in the 8th or 9th round en route to a close but unanimous decision. Today's fans may not know how good Nino was when he was "on". All these hypothetical matches must be with both guys at their relative best. You can't pick and choose from a guy's resume a fight where he wasn't on his best form, and Nino was superb at his best as a junior middle as well as a middle, and Oscar was not.
Bumdujour did say the fight would be at 154 though. I do think Benvenuti would win it (i can only really say at 160 though), would come in boxing and be able 2 use his strength to get it. Remember how bad Oscar looked against Sturm, even if the fight was at 154, Benvenuti will have that strength over his man.
Yeah, he was behind the 8-ball against Monzon, and would have been even earlier in his career, but despite being somewhat erratic at times in his championship tenure, he pulled it together quite alot and avenged most of his bad performances with style. Before he fought Monzon in 1970, he even showed some big time power, in his come from behind ko od Luis Rodriguez, and dominated and stopped Tom Bethea to get revenge for that upset tko loss. At his best, he was superb, a world class fighter, and not just some European champion.