The Aqua Lung was the US version of the Fifty Fathoms and only sold in the States.
I must dissapoint you Stephan, but I am sure that the 1000 feet was released later. The 50 Fathoms (like the name says) was the first 100m waterresistant diving watch besides the Rolex Submariner and both were introduced in 1953, so IMO the 1000ft-300m cannot be made earlier even if it looks older ;-) !!!
I think they start with the FF in Europe and released the 1000ft watch a few years later for the US market. ( IMO that sounds logical) My only date information about the Aqua Lung is that it was shown for the first time in the U.S. Divers catalogue from 1958, but I cannot tell you if this had the large or the small bezel. :-( In my opinion was this 1000ft Blancpain the first diving watch ever with a guaranted waterresistance over 200m!
Interresting is also the fact that the catalogues from U.S. Divers were called "aqua-lung" . Did Blancpain made a deal with US Divers (a sister company of Jacques Cousteau's "La Spirotechnique") to promote their watches in the US and that's why they choosed the name Aqua Lung for the US version?
In 1958 US Divers only sold two different kind of watches from Blancpain, the 41mm Aqua Lung 1000ft, signed 'Blancpain Aqua Lung' on the dial and the case, and a 34 mm version 600ft, signed ' US Divers Fifty Fathoms' on the dial (not Blancpain signed on the dial and the case) !!
I don't know how long they sold the 1000ft, because I only own the US Divers catalogues from '58, '64, '65, '66 and 1967, :-( but in 1964 the 41mm case sized 1000ft was no more offered.
I also don't know if the large bezel 1000ft had drilled lugs or not, I never saw one in real before!
Mine, the small bezel version don't has drilled lugs. I also don't know if one of these watches maybe were military versions? :-(
There are a lot of differences between the big and the small bezel 1000ft:
The big bezel had:
silver hands instead of white
small triangles near the 3/6/9/12 numbers on the dial
the 3/6/9/12 numbers were different in style and size
a slightly different 'BLANCPAIN' and '1000 FEET' writing,
but the most astonishing, in my opinion, was the 'AGUA LUNG' instead of the 'AQUA LUNG' writing
Because of the 'wrong' name and the small triangles (the first FF had them also) I do believe that the large bezel was earlier released as the small bezel.
Hope I could help you a little bit Stephan?!
best regards
Claude