Thanks everobody !!
About the movement, thanks to @dodo44
for you informations, finally it seems to be a 27MS rather than a 10.68N or 23M (see pictures below)
View attachment 498410
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View attachment 498414
Happy to have confirmation the watch seems all original
About the case my doubt was about the fact there is no Longines engraving on the caseback because I have seen some case made by PGF with the Longines engraving like this one :
View attachment 498420
(credit : Arno on a french forum)
: yes it's a 35 mm
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