Most University of California professors and staff would be forced to take between 11 and 26 unpaid furlough days a year -- cutting their paychecks between 4% and 10% -- under a revised budget reduction proposal presented by UC President Mark G. Yudof. The UC Board of Regents is scheduled to vote on the plan, and approval is thought likely in response to anticipated deep reductions in state funding for higher education. However, agreement by labor unions would be needed for large segments of the university's workforce across its 10 campuses.