Dear OF, Please tell me if its ori or fake? Case back is Ok?

 

It looks very nice - why do you think it may be take?

 

There is no „heritage” on case back and less informations

 

And the engraving on it seems of poor quality... Odd thing for sure.
The longines wording seems to space out to me, and of thinner font than it should be.
That's my take

 

From Longines website

 

I wonder if it was erased and then re-engraved (stolen)?