Re: Knowing what we know, would you pick a PEAK Dempsey to beat Tunney?
I think the Dempsey of Toledo would have been repeatedly slipping Gene's jab and countering with his right to Tunney's temple, as he did in setting up the Long Count knockdown. While we don't know how much better Gene might have become had he continued on after Heeney, we do know that a shot Dempsey had sufficient firepower to stun and drop Tunney when Gene was near the top of his game.
IMHO, Jack would never be able to floor Tunney for the count, but eventually the referee or Gene's corner would have no other choice than to stop it.
The Dempsey of the Willard fight wouldn't have grazed Tunney with that three punch barrage which immediately preceded Gene's hitting the deck, but would have landed all of them flush. At Jack's peak, he had no difficulties with accuracy. Tunney analyzed him brilliantly, but carrying out his strategy against a razor edged Dempsey would be a very different matter than dealing with a version which had been inactive for three years (or who didn't have a screwed up hip from Firpo's shoving him out of the ring).