Probably only Robinson or Mayweather and those aren't certain. Pea beat up Floyd's uncle pretty good after all
I struggle to find reasons Armstrong couldn't get it done over 15. Over 12, it's almost tipping point. But I could see Armstrong bringing faster pressure and starting to really cash in when Whitaker starts to fade (relative to Armstrong). You could see him being made to look dumb and small early and being right there late. Hurtful. Very aggressive, world cass fighters are your pick I think. And Ken Buchanan, obviously.
I think Benny Leonard, Roberto Duran and Henry Armstrong are about 50/50 with him. But just like with any of them I'd have nobody a favourite against Pea at LW. Henry Armstrong is possibly the best bet
I'd take Duran, barely. That's a 60/40 type fight IMO, Duran's feints maybe making the difference? Armstrong's non-stop pressure would definitely give Pea, and anyone trouble. Whether he'd win or not is a different matter, as Pea was awesome at out-smarting and out-manoeuvring aggressive fighters. I'd say that's a 50/50, maybe a 55/45 for Pea. Ike Williams is bound to pick up a win in a 40s-era multi fight series. And you'd be a fool to not pick Sammy Angott to beat him.
Armstrong, Duran, Hatton, Robinson are all clear favourites in my mind. Ross, Canzoneri, Ambers, Mandell, Mayweather, Mancini all have an interesting chance. I don't feel comfortable writing off Arguello and Williams. And there's the unpredictable LW duo of Hoya and Mosley. And lastly, Chavez had Pea received the decision in the first against Ramirez, would have been a very interesting fight hard to call even with hindsight.