The furniture set shown from your post IS NOT California Compliant. The stock CANNOT fold or slide; the pistol grip must have a device, wrap, insert to keep you from being able to grip it with your thumb around it; 10 round magazines are maximum. From the look of the magazine shown, it could be a blocked 10/30 or it could be a full 30 rounder, which you cannot bring into the PRK.
As Westie said, the HERA CQR is a very good compliant CA stock set. I have one on my AR9 One other consideration is that you cannot have a flash suppressor. Flash suppressors must be replaced with a compensator or anything other than a flash suppressor, including a thread protector (what I used on the AR9). Keep in mind, if you want to avoid registration as an "assault weapon", these are the rules you must follow. Also keep in mind that this is what CA DOJ says today; that is always subject to change or misinterpretation. The Commies in Sacramento are known to change rules or make up their own as they go. This fight is not over yet.