I reckon it could be a Nuovo Racing model. Check his site out:
http://bulgier.net/pics/bike/Catalogs/Bianchi-83/02.jpg
The rear dropout eyelets, painted fork crown and frame and Nuovo record components are what I'm looking at.
What's it worth? To a Bianchi fan - my guess - $200 (the asking price) as there are some parts missing and it is a bit knocked about as well as the 'wrong' colour.
Parting it out - could be worth a little more.
What would I do? I would think about a re-paint in celeste and a re-build according to the brochure shown in the 'bulgier' catalogue. I don't think it would harm this particular bike or its 'patina' value.