I guess Johnson out-riffs him to a decision based upon the styles but if Jackson is as god as Fitz says he was, Jackson may just plain old out-fight him. That's an unkown though so Johnson would be my own stab in the dark.
George Siler, the famous referee ,and the man credited with discovering Johnson said there was nothing between them for ability , but that Jackson had the better punch. As he saw both men fight, his opinion should not be dismissed lightly. Jackson took Corbett to a draw when he himself was carrying an ankle injury. I think we must assume he was "the real deal". I pick Johnson because he has a better record imo, but Jackson had some fervent fans among the fistic cognoscente.
Without footage it's impossible to say with any confidence. I do think Johnson belongs in a higher class though so i'd probably say tentatively he should be a favourite.
It would have been prety late in Johnson's career that this hypothetical match would have tipped in his favour.
That's funny because the complaint against Jackson during the late Sullivan run was that he did not have the clout.
I never saw him ,so I can only go by those that did. Siler did ,so he has more clout here than most I should think. Page 111 http://babel.hathitrust.org/cgi/pt?...e=100;seq=13;num=5;orient=0#page/111/mode/1up