Your source and chances of success depend a lot on what info you ultimately want. Original spec? Previous owners? You can:
Contact Porsche for a
Porsche Classic Technical Certificate. Formerly Certificate of Authenticity (COA).
Get in touch with forum member Dave Pateman who can often get delivery info on the car. What I believe would have been called a Kardex many years ago.
Try submitting VIN info to California Department of Motor Vehicles. I tried to do this for a couple cars in other states. It went nowhere, but you might get lucky.
Dig through anything you can find in the car like maintenance book, oil service stickers, etc.
Look in the
914 VIN databaseCarfax may provide some insight to ownership changes. Depending on how long ago it occurred.