..I find this whole pre-1960 Carrera idea weird.

I dont have any book or any access to hidden Heuer archives, but it is hard to believe in a weird story where Heuer produces a secret Carrera in 1954, hides it from the world until 1964, and then deliberately creates a huge publicity in 2004 to celebrate the fake 1964 birth of the Carrera so that the conspiracy can continue.

But... I don't doubt that this movement was used in the 1950s, I am ignorant about movements so can't comment. It's also possible Heuer produced a watch which looked identical to this Carrera dato except for the little "Carrera" name above the Heuer shield. I have seen some Carrera lookalikes with no name that probably predated the Carrera (admitedly not with this movement)...

...so that is my opinion, but I have zero evidence to back it up, just my own logic (and proportion).

PS: anyway my brother just got given a Carrera dato like this model to celebrate his 40th birthday, he'd be upset if he had to change his age to 50.