Prime versions. Who takes it and why? Let's assume Dempsey could get to 175 without affecting his performance at all.
Why don't we pit Pacquiao against Dempsey and assume Pacquiao can get to 175 without affecting his performance too?
Dempsey would stop Jones. Though out his career Jones used his phenomenal athletism and natural skills to dominate. I believe he knew his weakness was in his chin, and selected his opponents accordingly. Those men with pop that he did fight he was quick enough to evade, then he got old and lost a step, and the truth was exposed. While Jones would most likely make Dempsey look inept the first couple of rounds, Dempsey would not stop and would eventually connect, and the fight would be over.
BTW, This thread is ****. Different Gen's.. Throw Jones "as is" in Dempsey's day & let's see Jones Jr. try & last anything past 12rds. Let Jack pound on Roy's face w/The poor excuse they called gloves back then.. Dempsey would prob laugh his balls off with Jones hitting him with Everlast pillows.
Jones by KO in the 1st round. Dempsey would come out swinging wild creating a big target for Jones to land a well timed left hook to the chin of Dempsey....Dempsey was a great fighter, but his lack of defence wouldnt allow him to get close enough to Jones before eating many punches. His offence would be totally neutralized. In short, Jones would rearrange Dempseys face.
What? Dempsey entered the ring in his prime years weighing in the high 180s. Boiling down 12-15 pounds should be no problem at that size under today's guidelines. Plenty of LHWs enter the ring at 185-190.
Of course it's different gens, but we're just speculating here. Jones rarely got hit flush in his prime, so the gloves issue is less significant. And Dempsey had problems with smaller HWs such as Tunney, who is not appreciably bigger (although he did have a longer reach) than Jones. I actually think Dempsey had the right style to trouble Roy, but it's difficult to give Dempsey too much credit given the progress athletes have made since then and his own mistakes even at that time.