Details which can be determined by your close examination are:

close scrutiny of that serial number

OLMO headset?

Brand on hubs and rims?

Any name on hub wingnuts?

Brand of saddle and seatpost (if any)?

Brand of handlebars and stem?

One or two springs in Weinmann brakes?

Brand of brake levers and pedals?

brake cable braze-on stops on underside of top tube?

Is the bike repainted? If original paint, any traces of decals, particularly on the downtube?

Do any family members have recollections of when this bike was purchased and/or ridden? Ask around.

These will help fill in details so you can figure out the approx year and possibly the bike model... but I don't know of a lot of old Olmo model names having Brianza lugs. The decals seem to have been lost over time.

What I see on it in those photos:
Brianza lugs
chrome head lugs and fork crown
chrome stay and fork ends
Magistroni crankset
Agrati stamped dropouts with scalloped backs
OLMO seat post clamp
C966 or O966 serial number