Thanks Shaun, yes the slight gradients on the subdial sides really catch the light and give the dial proper depth especially outside. Frankly when I first opened the package I just stood with my mouth open like an idiot. Anyway a really helpful lady from Meister just replied... they co-signed many Heuers up to the 70's but she's adamant that they didn't add any numbers to the watches, according to her the most likely explanation for the 'B' number is that it was added in the course of remedial work at some point by the repairer (servicing marks would be, and are on this watch, inside the case of course). That would tie in with the serial number between the lugs not matching the number stated in a service book which came with the watch - I was assuming that the book simply didn't belong with the watch but if the outer case which bears the number was replaced at some point due to damage (with the repairer etching his code discretely on the rear edge of the new case) then that could explain the mismatch. The book shows sale by Meister in April 1970 with number 159120, compared to the later 162958 on the outer case now.

Anyhow, it probably doesn't pay to get too hung up on the details, just keen to get it back together and on the wrist !