I'd still go with Duran, mainly because I think the fight ends by KO and I think Duran pretty much had a granite chin. But he would have really have to close the distance and turn this into an infighting war, I think giving Loma space to get his punches off would be bad for Duran. Very good question, hard to pick either one of them with any degree of certainty, especially considering how green Duran was at 130 and how much amateur experience Loma has.
I think Duran would likely find a way and knock him out late. Loma would be on his bike as soon as he felt Duran's power.