Can you help to identify these frames, bikes or parts?

It's not that I believe it to be top end (I'd like it to be, obvs, but I'd accept it to be a mid-range tretubi model), and it's not that I doubt your many years of experience. It's just that your Scientologisr certitude that you are so absolutely right (the Bianchi catalogues are wrong, Velobase is wrong, Speedcycles is wrong, the man in the shop - who wasn't a man in the shop - is wrong), and that any suggestion of evidence to the contrary is to be ignored as loudly as possible, makes me want to double-check everything you claim.

• Your "virtually identical" 81 Del Mondo link wasn't identical at all.
  
• Your 81 del Mondo has now become a 80 del Mondo.
  
• "no chrome rules is out a high end frame" is now "no chrome normally = budget"
  
• 52cm is not exactly "much smaller" than a 54cm, for the weight. It's 2cm smaller.
  
• I still can't find any examples of 80s models with top tube cable clips, so I'm still inclined to believe this is more late 70s than early 80s.
  
  

Still, thanks for the information anyway, it has been helpful.