Thanks, guys, I'm definitely not an expert n Cartier watches, but I know clearly more than that.
Early Cartier watches in the 1960s and earlier had no secret signature in the dial.
And, yes, the movement is definitely wrong. That's most apparent in the fact that the case has been opened up, crudely so, to accompany the tonnau-shaped wrong movement. At some point in time, my guess is the 1960s or early 1970s, the round, ETA-based 2512-1 had died and was replaced.
There's a reason why I was able to get this watch for cheap. The seller has a top notch reputations, and sells the most amazing high end watches and watch parts professionally. I have no idea how he finds them.
Keep in mind this watch comes from Caracas, Venezuela, in terms of resources not much better than Cuba, so, yes, the butchered the watch case to install a movement to just get it going. I will either find a clean ETA 2512-1 or follow the watchmaker's advice on how to proceed.
For kicks, here's another Cartier with a wrong, in this case Concord, movement:
This is clearly an old watch, dating, at the very least, to the late 1960s. Could it be a complete fake, done in solid 925 Sterling Silver? Sure, but it's highly unlikely. I'm sure it's a genuine watch, with a later in life opened up case to accompany a wrong movement because they couldn't get a replacement or it was too expensive for the owner.
Still, while I wait for the watch to arrive, I appreciate all comments, good or bad.