Any idea what this is? - 1920s Radior

[Woz]

It's all a bit sad.

Back to the OP and sharing his hard work for saving and doing a great job.

They will never be reproduced as a whole nor on any quirky detail component level and the special ones are really worth saving.

Even if it's just to remember and have a glimpse of what-if-maybe history turned out different. The wrenching journey also counts like a ride

 

[Nabeaquam]

The less brutal approach (which I can already here shouts at the back of the class to wash my mouth out with La Petit Marseillais) is basically swap out the forks for something 1" and take the joy ride of messing about matching fork a-c and fork rake. Internal headtube cup diameter should be the same and you will get a bonus of being able to use a more standard quill stem and handle bar set too.

Horses for courses. But, by far the best advice I can give is above especially if you've got most of the original parts in OK condition.

Someone like @bikeworkshop ideally should routinely be taking weird sized candle stick seat-posts, headsets and BBs off any knackered / junk status French bike

Yeah, that’s what I’d do. I forgot I did this in 1975 on a French bike my brother in law crashed. I straightened the frame and replaced the fork. I don’t remember how I did that as the bike had smaller diameter tubing. Perhaps the head tube was big enough, don’t recall. I replaced the stem and bars, painted it and retained the cottered crank. It was a wonderful 10 speed. I must have dumped it when we moved. Good idea.