The Basilica is all around convoluted nonsense so a rework to that could be an avenue to buff Italy. Make the Papal units natives so you can have a bigger army. Add a Papal Basilica holy site with Papal Zouaves and Papal Guards as native units. Then set up the Basilica to train these as armies paired with units that cost population.
Swiss Guard
3 Papal Guards & 3 Swiss Pikemen
Noble Guard
4 Papal Zouaves & 2 Elmetti
Palatine Guard
4 Papal Zouaves & 1 Papal Bombard
Other Changes
Take Schiavone out of the Basilica because they have nothing to do with the Church. Put them in the Lombard, Fort, or even rework them into a cavalry unit.
Ditch Papal Lancers in favour of Elmetti. They are the same thing, with both being based on Lancia (An Elmetto is the head of a Lancia company, and the Papal army only briefly experimented with Lancia). The regular Elmetto could upgrade to Papal Elmetto with a charged attack if Papal Arsenal is sent.
Papal Bombards also are a made up unit. They could be simplified to something more like “Bronze Bombard” and only get the name Papal Bombard if Papal Arsenal is sent.