Hello.
It won't depreciate the car any to have it registered in the state you live in. Keep the black plates, so that, if you decide to sell it, you can show that it was a black plate California car when you got it. It all goes back to why being a black plate California car is a good thing. The reason is that, in certain areas of California, cars don't get rusty nearly as quickly as they would in a place like Detroit or Pittsburg, which means that it's probably a good, solid original car. However, during a restoration, you erase pretty much everything cool about being a solid, original car. It isn't original paint anymore, much of the interior will have been replaced, etc.. If it's still all original sheet metal, that's a good thing, but, a solid, all original sheet metal car from Nevada is worth just as much as one from California.
There isn't anything magical about being from California, it's just the possibilities that having been in California it's entire life imply. Go ahead and register car. It won't hurt the value.
1969 Mustang license plate state change? 
