the big concern is having too many units to transfer. You can take all the lower division classes you want and the total is capped at 70 semester units for purposes of admission eligibility, but the UCs will add any upper division units to that. If your total is too high then you won’t be eligible to xfer. See http://talk.qa.collegeconfidential.com/uc-transfers/2081175-uc-transfer-faqs-part-2.html and page 33 of https://admission.universityofcalifornia.edu/counselors/files/quick-reference.pdf