. . . you have there! I wouldn't say ref 168.005 is uncommon. While I don't know how many were produced, it's not a difficult reference to source. Your dial is a pie-pan - desirable, but again, not particularly difficult to find.
Automatic movements in the '60s were common . . . automatic chronometers, though, were a different story. My sense is the Constellation line was one of the most widely produced chronometers in that decade. The original owner was persuaded to part with more cash than necessary in order to possess an accurate wristwatch. He could've bought a Genéve or Seamaster or a competitor's model for less, but paid more to own a Connie.
They were then, and still are today, exceptional wristwatches. Congratulations on finding such a well-preserved example.