With the chrome headlugs it has to be an '80-'81. It's a top Reparto frame. It could have been originally sold as a frameset, or complete as a Super Leggera or Super Corsa. Looks like some of the lettering on the top-tube by the head-tube is still present. That would be the model name, or might say "Specialissima" if sold as a bare frame originally.
I suspect it was sold as a frameset, as the SL and SC models were all Super Record and had special pantographed and milled parts. This bike looks like mostly Nouvo Record, and the high flanges hubs were way out of style for a top end racer in 1980.
The top of the fork crown would have been painted originally but it may have started flaking and the paint was removed exposing the chrome underneath. Or it could have just come that way. There's no "absolutes" on Bianchi's of this period.
If you are into Bianchi's and it's your size you should grab this one. It's one of the best frames they ever made.