I and others have used ABS Power Brake, Inc to rebuild and refinish the booster. It took about two weeks to get mine rebuilt. I did have to call them a couple of times to get an update, since I was in a bit of a hurry.
I would recommend them.
ABS Power Brake Inc.
233 N. Lemon St.
Orange, CA 92886
(714) 771-6549
Regards,
John