James J. Jeffries vs Rocky Marciano. Who wins?

Question

Dream fight and 15 rounds. Modern rules and in their prime.

Answer 1

Early rounds:  Marciano attacks, but can't land anything solidly on Jeffries, who fights out of a crouch, and will tie guys up.

Middle rounds:  Both fighters go toe to toe, and are even.

Late rounds:  Jeffries weight and enormous strength becomes a factor.  He pushes the Rock around some, and mauls him with hooks to the body.  The Rock keeps coming, throwing punches from all angles, but is bleeding around the eyes.

Jeffries by decision.

Answer 2

Jeffries by KO in round seven

Answer 3

Jeffries - too big, too strong. TKO by round 12.