That is a fantastic find. It is the very first version of the Autavia wristwatch that Heuer produced. After 20+ years of production and countless different iterations of the Autavia, it is still the most elegant of all the Autavia versions (along with it's 2-subdial valjoux 92 brother). It is pretty rare and sought after by collectors. It will be important to have the original hands from the watch as they are special to this version and complete the design of the watch perfectly.

Here is a photo of some Autavias showing the evolution of the model from the early to late 60s (top row) and from the late 60s to the late 70s (bottom row); there was a further evolution in the 80's (not pictured). The first two (top left) are the "first execution" versions, the first the 2 subdial version with a valjoux 92 movement, the second the version you found, three subdial with a valjoux 72 movement.

Looking forward to seeing how your project develops!