Wonderful, boys!!!
I remember only (I was just a little child at the time...

) Spartaco Dini, winner of the race in 1966. And the accidents that happened, involving some spectators, in the Coppa Gallenga 1966, that caused the end of the race.
I'm not sure (and I remain not sure) if the race was a simple hillclimb or a sort of circuit. For example, Hans you wrote in 1958 "tratto Squarciarelli-Rocca di Papa,
2 laps". What does it means? Two laps of a circuit or simply two manches of the same hillclimb?
I said, I know very well this part of Italy: if you know the old italian song "Arrivederci Roma"

, in the text of the song there are the names of Frascati, Squarciarelli, etc. that are all little towns, or small villages in the hills near Roma, named Castelli Romani. Rocca di Papa is a fine village on the top of a 1000 meters mountain, so it's possible that the race was an hillclimb with the finish-line at Rocca di Papa. But Frascati and Squarciarelli, or Vermicino (named in Leif's records) are all
around the mountain of Rocca di Papa, NOT in the same climb: so I think it's possible a sort of circuit between those villages...
MYSTERY