just so you are aware, your link says Buttonwillow and then in the thread is Big Willow - you may want to be clearer as to which one it is
I am sure the link you gave is correct but it could mislead an interested party.
Also, given your intermittent health issues, it is good you found OTR and I used to run with them at WSIR. They are very open to late sign ups - you pay a bit more but they don't mind that you join day of event even. If you run with them then you may also be aware of ACRA - American Car Racing Association - which is "the other guy" - they both work together and alternate month to month who holds the event.
For everyone else reading this, this is a great group of folks to run with and they allow pretty much anything to run (ACRA isn't only American cars, I had my V8 Porsche and many 100% Porsche guys run with them). There are lots of Porsches actually at the events, some really good drivers in the top group that I loved running with when I lived out there a couple years ago, etc. Lots of track time with them as well. They used to have a catered lunch included, not sure if that is still the case, but hey, lunch included is lunch included!