There is much more expertise here than mine (like BG above) but I’m getting an ‘87 feel from this, especially with the fork crown. Fork sticker is Columbus SL. SL will have spiral ridges inside the fork steerer and no ridges when you look or feel inside the seat tube and down tube at the bottom bracket.
I think with the Celeste and the pantographing, yours will be at the higher end of the Bianchi desirability scale. The market is sluggish now, so if you put it on eBay as an auction, I would not recommend putting up for less than you want opening bid, because it seems like auctions are getting only 1-2 bids. I would try $400 BIN + shipping and see how it goes. The Campy headset is worth $30-$50 and that Campy branded spacer is like catnip to us Campy-holics making the headset worth a little more.
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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