In 1957, Rust was chosen as a replacement in Eugene O'Neill's Long Day's Journey into Night, with Fredric March and Florence Eldridge, March's wife. The play was performed in the prestigious Helen Hayes Theatre. In 1958, Rust signed a contract with Columbia Pictures, along with other young Hollywood aspirants Michael Callan and Yvonne Craig. He appeared in 1959 in The Legend of Tom Dooley, a Western film starring Michael Landon, unrelated to the popular song "Tom Dooley" released the previous year by The Kingston Trio. In 1959, he was cast with Roscoe Ates and Andy Clyde in the episode "Well of Gold" of the NBC children's western series, Buckskin, starring Tom Nolan. Rust was cast in 1960 in the crime drama film, This Rebel Breed, about rival narcotics gangs in high schools.