Tall, rangy fighters with great jabs and good hand speed are the best bet as he'd be out of range to counter. The problem is that he probably wouldn't fight someone like that. The only current fighters who fit that description and who can make 147 right now are Cintron and Khan IMO. All time... Robinson, Hearns and Prime DLH would decapitate him.
A prime Floyd is as fast as anyone, but he also had great ring smarts and timing. with these attributes, he could potshot opponents with ridiculous accuracy and then be gone. he is an exceptional fighter at every style he uses, and since he is older, the high guard is looking like his primary style now. which is appropriate. just another testament to his skills at adapting. prime mayweather is best staying on the outside. a slightly not as physically prime mayweather is best with the high guard in my opinion.