Those deep fishmouth stay ends (in my mind) place this frame in Emilia Romagna, in or around Bologna. The three builders that come to mind are the Patelli brothers, Ugo Chiesa and Rivola (who learned from Chiesa and had some frames labeled Rivola made by Chiesa).

The stamping on the bottom bracket doesn't look familiar to me but then Patellis and Chiesa did do a fair number of contract builds, so it could have been done at client's request?

Here are some random pics of somewhat similar features:

Patelli:














Rivola: