How would James J Jeffries stack up in the 60/70's heavyweight scene?

If he was truly a great fighter he would dominate in the 70's as he did the turn of the century. People tend to forget the dynamism of humans which allows us to adapt far faster than any other specie. We can do this so quickly it's almost instantaneous. So... When yzing fighters like Jefferies & Johnson, we must remember that they wont be burdened with the big elephant in the room called having to still fight in round 25 and will adapt accordingly.