CA does allow a limited number of plates for specialty build cars at the beginning of each year. This would include repros (aka continuation). It's first come on the plates. I think it's 500 state wide. Any repro car sold with CA plates will be $5000-10,000 more than if non-CA registered!
Ed
PS I've been a passenger in an ERA GT40 repro & a Butler GT40. As has been said, it is a rough animal. I roughened my FGT a little to get some of that experience but like the civility also.