I actually think Duran stops Arguello. I just can't get the Pryor fights out of my head when I think of this matchup.
Duran by close decision. Duran was tricky, but would be in front of Arguello for most of the fight and Arguello would definitely land his share of meaningful punches.
And Arguello would be right in front of Duran, which would be his downfall. The differance in this fight would be speed. Duran would make Alexis look like a sloth in there.
Duran is certainly faster but he didn't use his handspeed in the ways fighters with good handspeed typically exploit that advantage. Alexis was great at timing opponents and his great arsenal of punches allowed him to make up for his deficiencies in speed and more importantly footwork. Sort of like Marquez-Pac. Duran is an all time great in-fighter but Arguello would not be just overwhelmed.