What is the seat post diameter? I presume the seat tube outer diameter is 28.0mm (very French!). A seat post diameter of 26.4 or 26.6mm would indicate high-quality butted main triangle tubing, where straight gauge would take a smaller diameter, and plain carbon steel, smaller still.
I am not a fan of Sugino Maxy cranks, but they are better than cottered steel, and at least yours are the later version with a replaceable outer chainring.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069