Shibata beat a Saldivar who was no longer Saldivar. I would think that assuming Gomez moves up at his peak, and Gomez DID have fights at 126 before he fought Sanchez, that he would be plain and simple too good for a non-great like Shibata. Gomez lost a grand total of 1 fight in his prime... to one of the baddest MF's who ever put on gloves. He could beat Shibata.
I'm taking him from the form he was in for Sanchez, so right at the peak of his powers. And I think he'd win. Shibata was a gorgeous technician, and such an explosive, yet efficient pressure fighter, but he was far too fragile to maintain that vs Gomez IMO. I tend to think Gomez would know you had to put it on Shibata and not let him build a rhythm. Take him out early if you can. Gomez KO3 IMO. If not, he's in for a long night.