http://admission.universityofcalifornia.edu/counselors/freshman/minimum-requirements/subject-requirement/index.html#lang indicates you can use a 540 on the French SAT subject test to fulfill the foreign language admission requirement for UC. If you think that you can get >750, then you have plenty of room for error.
Here are some practice questions: https://sat.collegeboard.org/practice/sat-subject-test-preparation/french