What would an Italian version of the Atlanta class look like, and how useful would it be?
Short answerIt would look much like the Capitani Romani class, a useful design that Italy could not build in sufficient numbers.
NotesThe Capitani Romani class already occupied the niche imagined by the question: a very fast light cruiser or large scout with substantial gun power. The design was capable and potentially useful. Its strategic weakness lay in production, because Italy lacked the infrastructure to complete enough examples. A sound individual ship could not make its class matter in war without the industrial capacity to build useful numbers.