Please help me evaluate the originality.
I am interested, but my knowledge about 30ch chronographs is very modest.

 

Mine for reference: The crown on your watch is a replacement. Other than that it all looks complete. Must be a very early model.

 

Dial is original. Apart from chrono second hand, which may be original, hands are correct. Case is French-made so not certain about originality of the crown. From the early 1950’s based on serial number. Overall, a nice piece.

 

The case has been over-polished (the lugs should probably be facetted).

 

If I had a shot at this I’d pull the trigger.

 

mine looks like this:

 

it´s later but seems to be the same case.

 

I just got mine back yesterday. My mom bought it for my dad over 50 years ago. He passed a year ago today. It needed work so I had it sent to the Longines factory in Switzerland. They made a new crystal, crown, and replaced several internal components. It is as perfect as the day my mother bought it for my father. I would never let anyone but the Longines factory even look at it. The work they did defines "artistic and scientific perfection." They sent me the old parts they replaced, and will be forwarding me the certified history of the watch.

 

Lovely ... Now get a proper sized strap for it!

 

Definitely, but since I dropped $4900 for the work which took Longines 11 months to complete, the strap has to be a Longines original! During my next trip to Europe, I plan on passing through Switzerland where I will pick out the perfect strap.

 

Holy crap ...That's Patek $$$$$$!

 

I once sent a watch to be serviced and it cost over $2k. I thought that was expensive but they did an excellent job and it was well worth it. They have parts and expertise that few people have. That said (and to paraphrase @Larry S), $4900 is a lot of $$$$$$$$$$$$$!

 

Well OP is never going to sell that beast and it is worth more that the repair so no harm no foul I guess.

 

The watch is beautiful and you have the peace of mind that it was repaired by the best in the business.

 

lust lust lust

 

I'm fairly certain (actually 100% certain) an independent watchmaker could have done the same work to the same standard for under $1k, but to each his own. That's a gorgeous watch inside and out, Farzan. Like others have said, it's worth more on the market than the service cost. Plus with a history like that, it's priceless to you!

OP, the watch in your photos is in decent mechanical condition (though it will still need servicing unless the seller has proof). The dial is original and the watch was made for the French market.