Assuming it is a real Galmozzi (which I am sure it is) then two things - basic features and component dates and comparison to other examples. The basic features are all consistent with an early 70s bike - not a lot of braze-ons, single set of bottle cage studs on downtube, over the BB top cable guides but brazed on and not clamp on, 120mm rear spread, nutted brake mounts. Components all date to 72 or are consistent with 72 - PATENT 72 RD, FD with flat cage and no circlip on upper pivot, no date code crank arms, oval Milano logo Cinelli stem, 5 speed Regina freewheel. Brakes are not completely consistent with my 72 date. The drilled Super Record levers were out by 73 or so. The Gran Sport brakes didn't show up until the late 70s, certainly by the early 80s. The Galmozzi template didn't change much into the early 80s but they did adopt recessed brake mounting, brazed on shifter bosses and cable guides, etc. So I am pretty sure this is before 1980. I suspect the brakes and levers were replacements but they are the one question mark.

This bike matches very closely with this 70s Galmozzi on CR Galmozzi Jim Bolivar but is clearly earlier than this 80s galmozzi on CR Galmozzi 1983 bike

3-20170309_185133 by Jim Nusbaum, on Flickr

2-20170309_184812 by Jim Nusbaum, on Flickr

1-20170309_184803 by Jim Nusbaum, on Flickr