I do this kind of work and if I were you, I would order the death certificate for your father. That will give you some good, reliable information to work with e.g. you will most likely get your fther's exact date of birth. Maybe his mother's maiden name. California has their death index online:
http://userdb.rootsweb.com/ca/death/search.cgi will enable you to find your father's exact date of death which you'll need to order his death record. good luck. Belizaire