Funny someone said Zeus....because that was my immediate reaction...

Bottom bracket shell looks very much like mine (mine being a newer bike).
Fork crown ditto...but no side engraving.
Same lug cutouts.

I would say Razesa is a strong possiblity as well as they produced for Zeus.

But if it were a late 70s or very early 80s Zeus or Razesa - wouldn't it be French threading? If what you have is BSC or Italian then you pretty much eliminate Zeus / Razesa - correct me if I'm wrong.

=8-)