On paper, the more efficient way would be France and Austria allowed the Tuscany succession through the Farnese line, plus throwing a "blessed ruler" modifier on Charles (III). In 1737, Charles de Borbon, already King of Naples and Duke of Parma, becomes Grand Duke of Tuscany. He fights well in the Austrian Succession and gets the Milanese. He manages to marry the Massa heiress to his eldest son and forfeit the Spanish succession. He would be in good position both in the North and in the South of the peninsula. But, beyond an ASB protestant conversion of Italy or a French revolution-like event, the Papal states are still an obstacle to any political unification.