Well, you are in the right state for finding solid bodied cars. As long as they are truely been in CA their entire lives. My '67 400 was - I have the period correct black/yellow CA plates and the PHS documents to prove it. Several I looked at during my search in Dec 1997 were not.
I developed a CA license plate database where I can give you a pretty good idea if a local car is legit or not. So I could weed out the fakes. But I would spend the money for PHS docs before I would buy one.
PS, there were only about 1200 '67 400 coupes built for CA with the factory smog pumps.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI