I'll take Gavilan to beat Napoles in a great fight. I think Gavilan's size, ring savviness, cute / aggressive style along with his flashy offense will be more than enough to beat Napoles. Gavilan also had the stinging kind of punches that can potentially cut the cut-proned Napoles and cause even more problems for him.
Mantequilla, Napoles nickname fits. I think he'd outpoint Gavilan in a close one but I'd bet they'd split in 2 fights