Hi, I have a good private collection of bicycles Galmozzi, and know enough about Mr. Angelo Galmozzi, to say a few things about this frame.
The frame is not a late 50th , but is a early / mid 60th , it is clear from the way in which the pending join the saddle node.
It was probably replaced the handlebars and stem, NOT as I have never seen on a Galmozzi a handle bars of that type, as well as the wheels, which usually in Galmozzi were almost always composed of Campagnolo hubs and rims Flames.
however, an excellent bike, you were lucky

sorry my bad english