Yep, early execution 3641, as per the 1962 catalogue (and possibly earlier). I've never been too clear on 50s Heuers so couldn't say whether these were out before that catalogue too. Jarl's knowledge of this era Heuers is excellent, so a nod from him is as good a recommendation as you'll get, I reckon.

You're right about the crown too Guilherme, it's way too thick. But then crowns are an easily changed part, and we see this sometimes on early Carreras too, where the thin unsigned crown has been replaced with a thick crown (Heuer or generic).