Look into California Vehicle Code VEH §259 and Health and Safety Code - HSC § 44011. These are the CA regs exempting collector cars from I/M testing. AZ has a similar exemption for collector cars. Basically, just get collector car insurance then you aren't required to get an emissions test. I just registered my 72 last week - no emission test, just had to show proof of having collector car insurance.
Alternatively, maybe register it in another state first, then bring it to California. Easier said than done, I know. But, each State sets its own standards and regulations for vehicle emissions compliance (called I/M program) Federal law only sets minimum standards for individual states, tribes and some other regions to comply with in order to meet federal air quality standards. CA has the most stringent regs if all states, even higher than the min fed standards - most states only meet federal environmental standards. Some states don't have an I/M program because they already meet federal air quality standards. So, first register it in a state that doesn't have IM testing, then bring it to CA.
But, that's probably bad advice. I don't know if it will work, because I've never had to it and I don't keep up with CA environmental law anymore. Plus it's a foreign import veh which I've never had to deal with. But anyway, maybe worth looking in to as a last resort.
Or just hire a company that imports foreign cars to CA and is more up to speed on the laws.