We have a used Beck Spyder going through the plant for a total refresh currently. It is being gone through from stem to stern and is also receiving 2014 wiring and switch update as well as an all new interior. 2165cc CB motor with new 4:2:1 exhaust and Rancho trans. Handful of tasteful period correct options. It will be ready for sale in just a few weeks.
PLUS it is already SB100 smog exempt for CA and CA titled.
Obviously you are doing your homework, and regardless of what builder you choose, pay CLOSE attention to CA registration and rules as they are now VERY different from most states. New builds have a specific build/purchase path for CA, and used cars built as a turn key for another state (and first registered in another state) may not qualify to be registered in CA.
Also check out Beverly Hills Motorcars. Speak with the owner, Carl Wong, he is a great guy to deal with and keeps a large inventory of used replicas from various manufacturers.
Finally, feel free to shoot me an e-mail or PM and I can put you in touch with Beck owners in CA, both old and new.