A provisional answer about an Italian 17-inch battleship

Did Italy develop a battleship design armed with 17-inch guns?

The sources checked supported 15-inch projects but no 17-inch design, although a viewer later supplied an apparent counterexample.

The initial research into an Italian battleship armed with 17-inch guns found no such design in works on Italian naval architecture, Brassey's material, professional transactions, and John Jordan's studies. Those sources supported Italian 15-inch projects. An idea mentioned in conversation would not necessarily leave the same record as a naval design or construction project. A viewer later offers the Italia class as an apparent counterexample, leaving this negative conclusion unresolved.