Z parts are much easier to find if u don't mind aftermarket/reproduction.
1970-1983 Datsun Z and ZX Car Parts > Black Dragon Automotive > Car Parts
Or
Z Car Parts.com -- Motorsport Auto -- Home
To name a few. MSA is also having their annual Z show at the end of this month. Since ur in SoCal I would definitely recommend going. It's somewhere in Orange County.
-Jose