Runs about 4 minutes fast per day, needs cleaning and a new crystal. Unable to find "Excellency" model name or "6BC" movement in data base, but not confident enough in my knowledge to make changes. "LO" on case indicates 1950, but "A9" on movement indicates 1949.
There are lots of "Her Excellency" variants, so, now that you know what you're looking for, take a look at the vintage ads in the general 1949 timeframe (look at least a few years before and a few years after) and see if you can find your exact model. If you find it, post the ad in this thread.
Looks like this 49 Excellency BB to me. Does anyone concur? Last ad on the right.
In reply to I agree. The case details by wgcinder
Sure looks like a match to me. Another good job, Bob.
I wouldn't worry about the black numbers versus gold ones. We often see dial variations--many times much more drastic than just changing the color of the numbering. Bulova often started out with one type of numbering, like luminous or black, then changed to gold. Others on the site have more expertise than I do, but I think that most of them will agree with this assessment.