The tires are not original. But they are old, just not that old. This is not a big deal. Tubulars rarely survived a year on a bike, let alone 50+. I am a bit skeptical on the date too, but not by much. I would reference the patent date on the rear derailleur and the mfg. and the introduction date. 1950-51 would be more comfortable for me. Prior to the introduction of the Campagnolo Gran Sport. The 40's belonged to the Campagnolo Cambio Corsa.

From the images of the bike, having it serviced could well depreciate it. A mechanic with the proper tools and talent to preserve things is needed. If it were mine I would do it, and not be afraid to ride it with newer tires. Something from Clement. Most interested potential owners would want the same thing.

The value of these is quite variable, more referencing needs to be done to get a better mfg. date range, I think some parts like the stem have been changed out long ago. $1,500 is a reasonable expectation. Possibly more if and only if two bidders demand to own it.

The location of the bike will dampen the price, many who have purchased things from other than a Western European country assume there is a risk of the item arriving.