Congratulations!
I noticed that auction and I think you got a great deal on the bike. Of course, everyone is enraptured with PX-10s of the 1960s-70s [I'll admit I have two], but I think that your model is far more to my liking these days. Yes, over the decades, I've mysteriously become too fat and old to race or even to concern myself with how fast I ride.
I was very surprised to see that bike had Reynolds tubing. In the US there seems to have been a dramatic drop in the quality of the bikes imported during the 1970s. Beyond the PX-10 race models they simply offered the substantially lower range bikes with relatively heavy tubing. The European buyers were clearly more discriminating. As far as build quality, I think you are correct. During the frenzied bike boom of the 70s there seemed to have been a lot of sloppy work pushed through the factory doors. Not only Peugeot, Raleigh also comes to mind. Nevertheless, that bike seems to overall be a real gem.
You are very fortunate to have an old gent at the LBS who actually appreciates bikes and enjoys working with them. In this town, it is extremely difficult to find any shop employees who care anything about older bikes... which is probably why I get referrals from various shops which simply can't be bothered to take the time to fidget with old French bikes. I must be the US equivalent of your bike mechanic - who spends far too much time losing money on bikes I simply like to work on. Blunder over to my apartment with a set of Mafacs on your bike and you'll probably leave with new cables and housings in lieu of a cool beer (just cuz I can!).
In Japan you certainly have wonderful vintage-style accessories to choose from... and more vintage French components seem to reside there now than in France. Hope you'll have Honjo mudguards on that bike in future photos. I'll be anxiously awaiting progress reports. And keep the photos coming! Enjoy!