An interesting piece, Nathan. Looks as a real Pilot, indeed, even including the integral bracelet.
A Frankenstein chrono can be the first conclussion when checking the pictures of your watch but, then another one example with exactly the same features, which look very well put together, additionally? Perhaps, and I'm only speculating here, at its time this model was offered with the option of a slide rule or the rotating bezel/tachymeter scale shown.
Heuer and TAGHeuer name combination were common at the time of the transition, so you are right, it should not be an issue.
Dubois Depraz chrono modules were succesfully combined both with mechanical and electronic movements in 1500, 2000 and Pilot series from TAGHeuer, and in Eterna and other brands (I own a Kon-Tiki 1958 with this caliber combination). Even fabled Audemars Piguet still have them in use in some of their normal size Royal Oak chronos.
