I think Julian is too big. Anything could happen if Cuevas lands a great shot. But, Prime Jackson likely lands first and lays him out.
It's horrible to think of Jackson landing cleanly on a smaller man; the effect was devastating enough on those of equal or greater size.
Cuevas is basically up against a bigger, stronger version of himself. He always has a chance whenever he lands cleanly, but Pipino most likely goes down.
I agree with everyone above, Jackson too big, too strong, probably hits a bit harder and Cuevas telegraphs his big punches, it would end similar to Cuevas vs Hearns.
