Pep imo definitely wins by being such a great defensive counter puncher, but Pacquaio is one of the most unique offensive fighters to ever fight. I think his speed has never been encountered by Pep and probably matches up pretty evenly which nobody even came close to doing back in the 40's. They both have great angles, reflexes, footwork, stamina, and determination. Also I believe that Pep would take awhile to ajust in the sense that he wouldn't be able to keep his hands as low as he did back in the day or Pacquaio would be able to reach him with that speed and combinations.