Your best bet is to put that car on E-bay or here:
http://www.collectorcartraderonline.com/
You would do better if you found a buyer back east , they pay all the money for Cadillacs that are in mint condition.
If you need some help drop me a pm as I'm in the business and have many connections. If he wants cash quick I could run it at the highline auction in Riverside but he won't get all the money they only pay wholesale.
How much does he want?