Hi list. As Mark Bulger pointed out a number of Italian makers used these lugs. I have a early 60's Ideor which uses them. My Ideor is fairly similar to the mystery frame, but it has nicely thinned lugs and is equipped with Campy "long" eyeletted dropouts. It also doesn't appear to have a serial number , although I have never had the fork off to check the steerer tube for markings. Just one more possible make to consider.
As an aside, are Ideors fairly uncommon? There doesnt seem to be much mention of them in the archives , or on the net. Does anyone have a photo of a better model Ideor from about 1962. Mine is in nice original condition except someone painted over the factory light gray with silver. possibly they wanted a Cinelli but couldn't afford one. At least they left the red chromovelto on the headtube and seattube. Were there originally decals on the top tube or downtube? Mine has Campy hubs and derailleurs with Ideor marked Magistroni headset and Magistroni senior cranks. It must be fairly close to the top of the line. Thanks Greg Lone Langley B.C. Canada