I’d just apply broadly (lots of campuses) undeclared and have him select a major after a semester or 2.
I wouldn’t bother taking the SAT again - he’s already got a really solid score. With a 3.91 GPA. most of the UCs are going to be a reach. He’s got a sold shot at UCR and UCM. The others are going to be tough,
I"d encourage him to also apply to SDSU, CSULB and/or Chico and Sonoma if he’s looking for a smaller school experience. Apply broadly
Good luck