This would be quite close, they're my top 2 at the weight, but Gomez was overall better. Morales is a bit bigger and has a better chin, but Gomez had better technical skills and much superior power. 12 rounds, Gomez takes a clear UD in an excellent fight after hurting Morales a few times, over 15 and Morales very well may get stopped. At 122 Gomez was one of the most impressive fighters I've ever seen. Inconsistant, but very, very talented.
Over 15 rounds, Gomez is one who could do it. It's of course not set in stone, and may not be the likely outcome, but remember, NO ONE went the 15 round distance with Gomez at 122lbs. 36-0-1 (36) at the weight I believe, 18 of those title fights and the draw in his pro debut.
Gomez would give Morales all kinds of angles and land plenty of bombs. If Morales wasn't stopped he'd take a tough beating.