Newscopy: Buster Keaton takes racing seriously.... He greets Jockey V. Thompson after latter romps home in the Buster Keaton purse at Caliente.. with the swift California bred Sausalito.... Sausalito is by Moonraker and has won last two starts for Walters stable. Incidentally Walters, former Spreckels trainer, has copped five purses in last two Sundays with California bred horses... running under his direction at Caliente.