First, your last month's rent is probably already paid. It is the landlord's responsibility to require any deposit of an increase your last month's rent. Thus, so long as you provide your written notice to terminate the tenancy before the landlord requires you to increase the last month's rent deposit, you should be in the clear. Note however that the California law is unsettled on this question, as this guide helps show: http://www.dca.ca.gov/publications/landlordbook/moving-out.shtml (note distinction between the wording "last month's rent" and "security for last month's rent"). If the landlord drafted the lease thirty years ago, then there is a California rule of contract interpretation that says any ambiguity today should be resolved in your favor.
Second, you may be entitled to interest on the security deposit, either by contract or by law. As to the latter, this would be governed by any applicable ordinances of your city (typically rent control) rather than the law of California. Are you in a rent control area: http://dca.lacounty.gov/tsSecurityDeposits.html
Third, have you already asked the landlord for a copy of the lease? If the document cannot be found, then its 'essential terms' may be reconstructed by oral testimony. Your testimony might be the only and best evidence of the lease terms if you are the only one with personal knowledge. It might be reasonable to presume the lease terms were quite favorable to you because you did choose to live there 30-years.
Fourth, regarding the security deposit, determining what is reasonable "wear and tear" after 30-years will be very specific to your unique property situation, including repairs and improvements over the years.
Fun fact: Imagine if you had made your security deposit with an ounce of gold; a pleasant surprise to receive that back today!
the new landlord has an obligation to furnish you with a copy of the original lease and is responsible for furnishing you with your deposit back less any money being withheld for damage.