Assuming it fits you, get the bike and lose the stem shifters. By the way, in the late 1960s and early 1970s, Schwinn DID offer TwinStiks as an option on the Paramount, and apparently some people took them up on it! Campag. downtube levers show up all the time on eBay at very reasonable prices. SunTour barcons are a bit harder to find, and Campag. barcons are rarer still.
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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