Concerning the year range, I would pick the components which look like they are original to the bike. Pull them and see if any have markings that can be dated or look to Velobase.com for a manufacture year.

next find out about the frame, what diameter Seatposts is it ? What threading is the Bottom Bracket(BB). What are the drop out spacings front and rear. Is this the original colour.

where are you located ? Are there any long time bike shops in your area that might recognize the bike or sold them.

Detective work is what needs to be done for this one. Some enjoy this, others find it maddening...

I think it is kinda cool for a Bianchi and yes, looks like early 80's or late 70's IMO.

Not 70's... Cable brazens on top and bottle cage brazens

Good luck ! Let us know what you find out.