Jones would miss a lot vs Johnson who was smarter defensively and he would make Roy very negative by countering him very well the way the lesser Griffin did vs Roy in their first match, trying to bullrush Johnson like he did in the Griffin rematch would be more difficult, Johnson would have toyed with Griffin. The first hook Cooper landed the fight would over, Jones doesn`t have a better chin than Ali.
Good selection of opponents. A case can be made for RJJ winning all the fights....and losing all the fights. To beat Jones...the opponent can't let Roy be the "front-runner". My picks: Jones outpoints a cautious Machen, TKO's Cooper on cuts though behind on points, and loses to both HJohnson & Maxim on points since both guys fought and beat some good heavyweights.
Of the 4, I would definitely give Maxim the smallest chance of beating Jones. I find it hard to imagine, how he would be able to do that!
Check out Maxim's record. Beat both Jersey Joe Walcott ....and SRR. Maxim because of his experience, wouldn't be intimidated by anyone basically his own size, and in 15 round fights would just do his own thing.