Pein wins very high difficulty. Hiruzen seems to specialize predominately in ninjutsu and taijutsu. His ninjutsu will be useless against Preta Path or Deva Path, whereas Animal Path, Asura Path and Deva Path makes taijutsu difficult.
Considering that 59 Hiruzen was said to be > Prime Orochimaru, it's safe to say that Prime Hiruzen would be a very good match for Pein, but he doesn't have any way to get the drop on him before Chibaku Tensei or Chou Shinra Tensei ends him.