You have more information than the CA Birth Registry. On the Registry on Rootsweb you can add a postem note. Perhaps if others are looking you will connect with them. In Rootsweb, choose searches, then scroll down to CA Birth, Death indexes. Select Birth. Enter information. San Diego County (has space between San and Diego). I believe you can only get the original certificate if you know the birth-mother's maiden name or the name of the child at the time of birth.
Personally, I was looking for genealogy purposes only. I gave up and contacted the cousin directly to get his birth name.
Best of luck, maybe someone with more legal savvy can help further.