What is the seat post diameter? It should be stamped on the post, below the insertion mark, so you may have to remove it. Can you post a pic of the rear derailleur? From what I can see, it appear to be a Z-series. If so, that would place the bicycle mid-1980s and most likely upper, entry level.

The Bianchi dropouts are interesting. I don't recall the owners of Gianella ever mentioning that they sourced via Bianchi. However, Jim Miele did source bicycles for Bianchi and we know Miele provided to Gianella, so that could be the tie.