Italian lock on combo rifle should be good. There are tradition, know how, and final look, etc.
As long as rifle barrel shoots bullets and smooth bore shoots shot shells should be OK.
I would worry about shooting slugs from smooth bore, with smooth bore being aligned for slugs to rifled barrel.
I know few acquittances of mine, drawn by attractive price and overall look bought newer Italian combination guns for driven hunt, where smooth bore slug is necessary, and ther were very dissappointed.
To be honest, one of those was some Sabatti, the other I am not sore. Not necessarily FAIR company.
Pricewise, combination gun costs, and if I were to buy new one it would be of German make. I would not test my luck with Italian combo guns.
On second hand market, best buy: Brno Super, old phased out Checz combo gun. Brno Super is arguably the best Checz combination gun ever made. With some luck it could be bought with few sets of barrels. Shotguns, combination, double rifle. As much as we love ZKK 602, and CZ 550 rifles, Brno Super holds the same status in combo gun world.
Brno Super, photo from internet: