I'm not particularly expert on Bianchi but that is a higher end one. My guess is around 1980-82 based on under BB cable routing and portacatena dropout. The rear derailleur is Super Record. A racing Bianchi from this era would be Columbus SL but the 27.0 seat post suggests otherwise and my guess would be Columbus SP which was used on larger size frames (like a 59 maybe indicated on the BB?). Another possibility is maybe it is SL and the seat tube just needs to be reamed out. The BB is almost assuredly Italian thread on this one. Cool bike!
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N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '82 Colnago Super, '95 Gios Compact Pro, '95 Carrera Zeus, '84 Basso Gap, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, '84 Paletti Super Prestige, Heron Randonneur