Indeed a beauty.
I'd guess no later than '65. That generation Huret derailleur wasn't used beyond about that. If you can find one, a Simplex Juy 61 Export would look nice. Whatever you choose, I'd stick with a '60's vintage derailleur set. The '62 Peugeot UO8 I'm working on had DFV wingnuts on "Top Star" hubs laced to the same Rigida rims.
Post some pics when you get it cleaned and tweaked. Nice bike.