You can't just put handspeed aside. Meldrick Taylor had all time great handspeed. He was an undefeated champion and at the time at his peak. He also had a tough neck and a huge heart. He gives just about any 140lber serious problems.
He wouldn't trouble Mantequilla very much...he'd be getting that wide open face of his turned into hamburger before he'd get knocked out by Napoles.
The Julio of the late-80's takes this one in a late round beatdown. There will be blood. People let that latter-King puppet version of JCC cloud their judgement. He was an ATG by the time he tamed Taylor the first go around.
Chavez' best bet is to reach that tender tissue and open Napoles up but that would be unlikely. Chavez lost a bit of effectiveness once he got up to 140 (age and career stage as well). Napoles was perfectly suited there. Napoles has some pop too and between that and just how damn sharp he is in countering (and willing to let his hands go) it's not like Chavez can take liberties. I'd look at Napoles around 9-6 in rounds. As Chavez tried to come on he'd have the answers.
Not sure at 140. It would be very close either way. No chance of Chavez getting stopped by Napoles at 140. Guy was made of iron.