When Tunney sparred the near 60 year old Corbett, he said that Gentleman Jim; "was brilliant. He still had bewildering speed. He mixed up his punches better then practically any fighter I've ever seen. Imagine, fifty-nine years old! It was the greatest demonstration I've ever seen in the ring. I learned plenty." Can Jim get it done?
The sparring session was not real was just messing around. Corbett sure was very talented and a great boxer but thinking the game progressed and Tunney would have been better. Key thing is which rules would be used. Corbett era rules gives his some help.
Corbett's speed, mobility, heavy feinting, awkwardness and unwillingness to engage would frustrate Gene at first, might give him shades of Greb in certain aspects. That said, I think he would eventually find his mark late and win most of their exchanges. Jim would need to make it a low output jab-fest to win but would Tunney show him enough respect to let it happen? Doubt it.