It is a mid-level bike, ca. 1964 vintage. "Gran Sport" refers to the Campagnolo derailleur group. I am guessing it has a plain gauge carbon steel frame, because of the lack of a derailleur hanger and the very plain head lugs. The fork crown looks very much like the one on my first (1962) Bianchi. The right crank and spider look like a single unit -- in fact, the crankset looks identical to the Agrati set on my 1960 Capo, although Bianchi may have had yours privately labeled (I cannot read the brand name of your crank). Although it is not a high-end Specialissima, its geometry probably makes it a great rider.
You may be able to find date codes on the rear derailleur, the cranks, or the hubs.
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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