I can recommend Sundance Cycles in Agoura Hills (www.sundancecycles.com)- they are outstanding and very experienced, and very prompt. I'd drive out there and let them take care of it because I'd know it would get done right the first time.
I would stay away from Veloworx in Brentwood - they will himm and haaa for weeks and not get a damn thing done.
Just my experiences - haven't let anybody else build a bike for me.