He was a close friend of Bruce Lee, under whom he studied martial arts. Lee was featured in the Silliphant-penned detective movie "Marlowe" and four episodes of the series "Longstreet". Silliphant reportedly recommended Lee for action choreography work. They had been working on a philosophical martial arts script, "The Silent Flute" (later known as "Circle of Iron"), which was to star Lee and James Coburn, and the pre-production even went to the extent of all three going to India on an unsuccessful location hunt. India was selected because Warner Brothers could not repatriate money their films generated in India due to foreign exchange regulations. The Siliphant, Coburn and Lee project was greenlit on the condition that the film would be shot in India to use the money unused in Warner's India accounts.