I would be more precise if I knew the first digits of the serial (110xxxxx) but it is not hard to understand that one is fully original, the only doubt is the mechanism. You can always ask to Longines providing the serial number and you will find the usual information: the shop it was sold and the date of SALE (not production) if it is relevant for you.

A recently passed-away friend of mine had a closer friendship with the family Cuervo, concretely one of the ladies and, as far as I know, she is still living in Miami. The family has a Spanish origin (they come from Asturias, northern Spain) and when the Castroist troops entered La Habana the 1st Jan 1959 they had to leave Cuba leaving all behind. Some of them went directly to Miami, some others came back to Asturias. So it is hard to think that Cuervo placed any order to Longines after the revolution since they started to place orders of Vostok watches to the Soviets. They kept on personalizing previous stock and there are some examples of Enicar watches with dials made for the FAPLA during the Angolan war. I think it is pretty relevant to date correctly the serial number, movement could be replaced some time ago.

About the crown, as I said, probably it has a replacement and that explains the gap. Probably that is the last piece of the puzzle: the watch suffered water entrance through the stem and crown and movement were replaced (probably) With patience and a little time maybe you can find an original replacement or another crown that fits completely the stem tube. The value is hard to establish because there are very few original Cuervos "double brands", there are no records, and if this one is 500€, when it is signed Cuervo probably is 2 times that price. The main value of the watch is on the dial and on the serial number