Hi Sam,
I have purchased headers and pipes from these guys:
https://www.westonuk.co.uk/Genesis-Pipes/
I had them make me some custom wrap around headers and they were very helpful and prompt both communicating and completing the work which is very nice and durable. I have one header on an OS 95AX with more than 500 flights on it.
I don't know where Rancho Santa is located in California, but I recently read on RC Groups that there are 5 classic pattern events scheduled in Southern California this year. There is very little activity here on the east coast, though there seem to be interested pilots.
Regards,
Will