Do NOT go to The Gun Shop in Lancaster, CA. They are completely disorganized, unprofessional, and do not do the work that you ordered.
I had a Garand with an CAIreciever on it that I wanted replaced with a Springfield Armory reciever. After having the gun for 3 months (It was honest to God lost for two of them), I get it back, and it has this IAI, Houston, TX peice of trash reciever on it. I asked them about it, and I remember their exact words:
"Oh, it's a Springfield Armory reciever, it's just stamped IAI."
At this point I was just so frustrated, I took it home with me without asking questions. I called Springfield Armory, and they said that no, they don't do that, and that all of their Garand recievers are made in Australia, but they can't do anything about it. IAI, of course, has been out of business for quite a while.
This is the type of service you get at The Gun Shop in Lancaster.
However, I'm in San Luis Obispo, and I reccommend Four Seasons Outfitters on Higuera St. If they can't do that work, they can point you in the direction of a reputable establishment who can.