Hi TomassoP

You've probably heard about the Sangro near a Town called Castel di Sangro(AQ) right in the heart of the national park you mention. Great Fly Fishing for browns. I think there is a NK beat there too.

You may also want to try the Nera river in Umbria (Borgo Cerreto) for browns and the Tevere Tailwater near Sansepolcro (Arezzo)for browns and grayling.These are all in central Italy. Let me know if you need further help.

Moreno