I bought it at auction, and the auctioneer who I know personally told me it came straight from the family of the original owner. It has clearly been used, and I serviced it on receipt. It was fitted with incorrect chronograph counter hands (the white ones) so I found some vintage replacements. I also fitted a contemporary 1039/516 71/1 bracelet.

 

There are only around 20 known examples of both types (Professional and non-professional), and this is the applied metal logo non-professional version, based on early dial layouts. I think this non-pro version is the rarer one. The most that one of these has sold is $212,000 by Antiquorum.

 

It also has the Omega extract, mentioning the Black Racing dial.