I strongly favor Mosley here. He's much bigger, stronger, with far longer reach, hits way harder, and possesses a better chin too. Mosley is great athlete. That being said, Loma is WAY more skilled boxer than Mosley could've ever dreamt of. Once Mosley lost his speed, he became an average boxer (see Mayorga 1 , Floyd, Pac and later fights). Mosley also had many technical flaws which made him so easy to read by certain fighters. That's why prime Mosley was completely dominated twice by Vernon Forrest and Winky Wright (both weren't nearly as gifted athletes as Mosley, but more skilled boxers). But Loma is so much smaller than Mosley or his opponents who defeated near-prime Mosley. I don't think he overcomes the size and strength difference. IMO Mosley stops him, that's the most likely scenario.
If Loma was on the same strong “vitamins” Sugar Shane was known to take, it would have been a close fight. Vernon Forest owned the greet Mosley yet no one called Forest a great fighter.