Walcott had success against Marciano, a fighter both similar and different to James J. Jeffries. It's an interesting stylistic matchup, who would you favour?
Walcott boxes, rips to pieces the face, and can completely outclasses Jeffries. Give Jeffries credit for being a tough tough individual but either he’s stopped on cuts even by the rules of his day or stopped knocked out by a punch he doesn’t see coming. Walcott to skilful, fast and cute. Don’t know if Jeffries had the punch to down old Jersey Joe but he certainly didn’t have the speed or skill to do so. Not taking anything away from Jeffries but the two fought in such different eras it might as well be a different sport. Just my opinion.
Walcott would outbox him, and stop him, most boxers from that era would beat most from Jeffries's era, boxing evolved a lot in that time period.
In the 1967 computerized all-time heavyweight tournament, Walcott vs Jeffries was one of the matches in the opening round of bouts. As I recall, opinion was divided among the experts as to who the winner would be. The computer fight was scheduled for 15 rounds and Jeffries stopped Jersey Joe in the 10th. As stated in a previous post, I believe the championship distance would have a lot to do with the result. The longer the fight, the more it would favor Jeff. Fights of 20 rounds or longer were common in Jeff's day and fighters trained accordingly. If this fight were scheduled for 15 rounds, I am inclined to pick Jeffries. Jersey Joe would certainly be capable of pulling this one out, but keeping in mind that he appeared in eight championship fights and was the underdog in every one. Of those eight, he lost six. Jeff carried power late, could take a beating and turn it around with one good clout. JJ arguably deserved the verdict in the first Louis fight, but he could ill afford to take it easy in the later rounds. It would certainly be a fight worth watching!
That was the computer tournament that later determined Jeffries beating Ali also, I believe. An indignant Ali sued or try to sue re that result, but apparently from there, Ali was persuaded by Murray Woroner to negotiate the computer Super Fight vs Rock Marciano, filmed in 1969 and released in 1970.
Over 15 rds I'd have to give Jersey Joe an excellent chance of outboxing Jeffries. Unlike Corbett,who ran Jeffries very close , Joe was a good sized, powerful heavyweight with significant power,I think he lures Jeffries into traps and punishes him with counters.Jeff survives the 15 rds but is badly marked up at the end of the bout.
Using a 1967 computer filled with vacuum tubes and copper wires I bet I'd have a good chance of defeating Jefferies and Ali in the same day.