Talking about this mystery frame:
I think the lugs are from Emilio Bozzi. Steven Maasland would know. Lots of Italian builders used them, so we aren't going to be able to narrow it down from the lugs.
Here's a pic of some lugs that I'm pretty sure are Bozzi:
I've seen that crown around too, also an item common to a few builders. I'm pretty sure it's this one:
I agree with those who've speculated that the dropouts were replaced some time after the frame was made. At the very least, the fender eyes were added later; that's a custom add-on that would not have been lavished on this bike when it was new. Sure, bikes like that came with fender eyelets, but only the ones that are integral to the dropout. These were brazed on separately, a fairly finicky job not usually seen in a high-production scenario.
Hope I'm not upsetting the owner, but most of the workmanship looks like several steps below a pro racing frame. Solid and reliable no doubt, but little to no extra effort put into making it beautiful, such as thinning/tapering the lugs. And as we know, thinning the lugs makes the frame last longer if the tubing is very thin and light, so it's not just done for beauty. These thick, relatively crude lugs and the apparent age of the frame indicate that the tubing is most likely also thick, for the frame to have survived without the fatigue cracks that thin tubes are prone to, next to thick untapered lugs.
As Victor Hugo put it, "The beautiful is as useful as the useful. Perhaps more so". Though he probably wasn't talking about racing bikes, he might as well have been.