Track Map of the Past: Pomona
You can still make out most of the course on Google Maps. Looks like the 3-4-5 sequence has been completely trashed. Though it looks like you can still faintly see the short straight bit at 7-8-9. I understand that this facility was in use as recently as 2012 for police training and the occasional Porsche Club event. In any event, it looks like it could still adequately facilitate a small bore race.
I was there at a PCA track day in 2013. The layout then was close to the original circuit, save that corners 4 and 5 were gone.