back then, in comparison to a prospective (hopefully) fight at 147? Probably a more aggressive, fast paced fight overall and less potshotting.
Do you mean the Pac who fought Diaz vs Mayweather at 135? Then yes, it would be a great fight, and I think Mayweather wins that one. Younger, faster than now, threw combos, more aggressive. Now Pac wins.
If the skill level is that of when they were at those respective weights, then floyd may have had a better advantage, but thats only because Manny has continually developed since then. But what if you took their current skill level and reapply it at that weight?
At the time, they weren't really weight drained, those were weights they were proficient at. They just got bigger naturally as they slowly grew older.
Would have been a better, more competitive fight IMO. Mostly because they would've been closer to the same size which means Pac's power and aggression would bother Mayweather more so than at 147.
Floyd wins big. He held a lot more power down at 135 as opposed to 147, he was faster, and a lot more aggressive. I'd see him using Pacquiao's aggressiveness against him, whilst going for a late TKO. The bout at 147 will be a lot closer in my opinion, but Mayweather will win via SD or UD.