I would say that it is worth your time calling up Margaret and sweet talking her. She is somewhat curmudgeonly, but also can be very sweet if you get her at the right time.
Case in point- I was back in Albuquerque a month ago, and stopped in to drop off my tach & speedo. She came outside to look at the car and asked me if my fuel gauge was working properly. I said that it worked welll until athe 1/4 tank mark and then was unreliable. She told me to take it off and she would fix it for me on the spot. She not only did that (which was amazing to watch on the spot), but also fixed my tach while i waited. She also showed me all of their old 60's testing equipment and filled me in on the history of gauge repair pre and post nissonger (she worked very briefly at nissonger before starting up her own shop in California She then moved to Albuquerque a few years ago). It was very cool; she is a wealth of knowledge.
On top of that service, she gave me the fuel gauge rebuild for free. I have to say that the tach & speedo rebuilds were pricey- about $340 for both of them (my speedo was trashed apparently. However, her shop's work is excellent and well worth it. She guarantees her work too.