Probably quite well, better than he was able to do in his day even. Most guys who'd have the offensive skill to deal with him just wouldn't be able to weather his attack imo, many of them are quite a bit smaller as well. Bradley, Paulie, Alexander, Khan, Brook, Broner, Vic Ortiz, Alvarado etc. Then you've got some really tough/dangerous guys who just aren't good enough. Guerrero, Provodnikov, Rios, Thurman etc etc.

Would only be confident that Floyd, or Pacquiao of a couple years ago would definitely not lose to him. Cotto and Mosley basically fought Mayorga when they were just as past it as he was, so I think you can kind of go by those results.

Would certainly be a riot if he were still around, but I suspect he has himself to blame for not taking his career seriously enough after the Spinks loss.