When the script was written in the 1970s, which film was planned to star Steve McQueen and Diana Ross?

"The Bodyguard" is a 1992 American romantic thriller film directed by Mick Jackson, written by Lawrence Kasdan, and starring Kevin Costner, Whitney Houston (in her acting debut), Gary Kemp, Bill Cobbs and Ralph Waite. The film follows a former United States Secret Service agent turned bodyguard who is hired to protect a famous actress and singer from an unknown stalker. Kasdan wrote the film in the mid-1970s, originally as a vehicle for Steve McQueen and Diana Ross.

Terrence Stephen McQueen (March 24, 1930 – November 7, 1980), known as Steve McQueen in his film career, nicknamed the "King of Cool" (during moto races used alias Harvey Mushman), was an American actor. His antihero persona, emphasized during the height of the counterculture of the 1960s, made him a top box-office draw for his films of the late 1950s, 1960s and 1970s.

Diana Ross (born Diane Ernestine Earle Ross, March 26, 1944) is an American singer, songwriter and actress, born in Detroit, Michigan. She rose to fame as the lead singer of the vocal group the Supremes, who became Motown's most successful act during the 1960s and one of the world's best-selling girl groups of all time. They remain the best-charting female group in history, with a total of twelve number-one hit singles on the US 'Billboard' Hot 100.