I was told recently by Stark that the California registration problem is that Stark is still not an option on their drop down list of manufacturers.
Some states have an option for "other," but no such option in California.
So I'm not sure, but I would think that if you buy it now in another state and get an MCO, that you will eventually be able to register it in California after Stark exists in the California system.
Edit: perhaps
@Swank171 can provide first hand info...