Bob Fitzsimmons gets all the comfort s of modern training, fit to fight in the 1990 s. He brings with him that freakish power. Now put him in with Benn, Eubank, Collins, etc fighting at 168lb .
With the caveat of "who knows?".... certain attributes are translatable to any era, power, timing and chin being at the forefront. Bob had those in spades. He is a top ten all time great pound for pound. Were I forced to make a prediction, I would predict that he would waste all those guys. And he would have no problem getting down to 160 either.
I agree, I think his power alone would have the supermiddle s and down ( and up possibly)wary of getting in to the ring with him.