Jackson is an interesting one. It really does seem, in the early days, as if Jackson was regarded as quite a bit better than Fitz and doesnt seem doubted by most (perhaps even Fitz) that Jackson at his best would beat Fitz. It is hard to really tell why, just looking at Jackson's record, but he clearly must have been something special. I could be wrong, but i think it almost certain that Jackson and Fitz would have fought at Larry Foley's hotel. I am guessing that no KO or decision would have ever been rendered in such fights. It is interesting though, I know that Jackson was once once quoted saying that Fitz was too nice a person to ever make a fighter. And it seems that most didnt consider Fitz Jackson's equal, even though he later went on to do what prime Jackson couldnt do. I have never seen Fitz comment on his chances of beating Peter Jackson, but it would have certainly been interesting to do so. And also to read of any sparring matches between the two.
When Peter was King of Larry Foleys,Bob was but a novice lightweight. A I think you're correct in that they dis spar. Fitz always seemed in awe of Peter.
You could well be right on the size issue. I find it hard calling him a heavyweight, it just so happens his opponents were heavyweights. His accomplishments at the weight are impressive, on par with tyson i'd say.