As far as I know the father of his Throttleman Rossi worked for Riva. Carlo Rossi developed the twin step Monte Carlo 27 and set up his own business in '73/'74. The company went bust. In '88 Gianfranco Rossi reanimated it with financial help of Della Valle and started to build 30' and 40', later 38'and 46' Monte Carlos plus a 32'.
I think you ask because of a used 27' boat that is always advertised as a Riva. I think Rossi developed it while he worked for Riva but built it later in his own shipyard, so not really a collectors item for Riva fans.