If you keep the friction shifting, you have myriad options. If the cranks are in good shape, just look for a set of 144mm chainrings on eBay -- this is your big chance to depart from old school 52-42 orthodoxy. Otherwise, look for an entire crankset and a new Italian thread bottom bracket, perhaps a sealed cartridge.
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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