That would be a rough fight. They would fight with everything except knives and guns and, if it was scheduled for 15, it may come to that.
My cash is on Fullmer, I think Jake while very strong would be overmatched here if you’ll remember Gene’s bout with Robinson he had an interesting game (the first time) and took very little damage on his way inside, I think he’d do all his work on the way to getting in, landing a few good punches at a time and like with Robinson he’d lock LaMotta up and frog march and wrestle him around off balance so he can’t get going at close quarters till the ref separated them. I don’t think he’ll tire JL out with this way of fighting but I do think he’d neutralise LaMotta with this plan and land the clean shots for the decision, LaMotta also can’t really hurt Fullmer bulling his way in the way Robinson famously did either, Jake didn’t hit very hard for a 160lber.
Much as I hate to admit it, I lean towards a Fulmer decision. Neither man is stopping the other in this war of iron chins