I'm probably not telling you anything you don't already know but there is a Riverside International Raceway Museum located in the Inland Empire. I found about it when a flyer from the Local PCA in Riverside was sent to me to attend an automotive detail seminal.
Here's their website, it's pretty lame but it does give information on who to call for reservations :
http://riversideinternationalraceway.com/_wsn/page3.html