I feel Pac's main disuading factor would have been his power. Barrera dealt with the power of both EM and Prince pretty well, so I feel a prime Barrera would only have difficulrty if he made the fight hard for himself.

As for prime Morales, I feel that he could have dealt with Pac much easier using his boxer/puncher style.

I actually think another guy who could have challenged Pac would have been McCullough at the lighter weights. With his chin and style he could have dredged out an exciting loss to Pac.