: And will the movement be identical to the original Heuer?

It depends on the age of the relative movements. The cam lever had three different designs throughout the life of the Vj 7733; it shouldn't make any difference to the operation of the watch externally, but does mean that it potentially isn't quite as 100% interchangeable as it might have been. Your watchmaker should be able to hybridise the two if necessary but I don't know the extent of knock-on changes to the design.

I don't think there is anything major and you should be able to cannibalise in either direction, but I wouldn't want to guarantee it as I'm not a watchmaker myself. Though I wouldn't mind trying at some point, anyone want to send watches for me to practice on?!! Kidding, though I might trawl the car boot sales for some cheap mechanicals in the future.

Valjoux typically offered the movements in 3 or 4 different degrees of finish too, but those differences are often more cosmetic than significant. Sometimes it did mean different materials in a component or two (steel vs brass, for example) but those were often changed as the movement evolved anyway.

So the answer is a guarded "maybe" :) The transplant should work, but it might not be identical down to every last piece.