Older cars usually need a Dealer, a Dealer will import them from Italy. if you don't have any in a scrap yard then you have to do to the Dealer.
I live in London England and Occasionally I have to go to the Dealer, they have to import my Parts from Italy.
You might want to try some car shops or part outlets in your area for pattern parts. not original Fiat parts but parts that will fit your Fiat.