Dick Cavett. British author Jan Morris (nee James Morris) explains why she underwent a sex change operation. Ch. 5, 12:30 a.m. 1 1/2 hours.
Brother Rat (1938). Eddie Albert, Jane Wyman and the governor of California star in a comedy-drama about life at West Point. Ch. 27, 7 p.m. B/W, 1 1/2 hours.
Forever Gershwin. A tribute to the late composer, who would be 75 this year. Ch. 5, 7:30 p.m. 1 hour.
Spartacus (1960). An early Kubrick film with plenty of pomp, violence and massive crowd scenes. Screenplay by black-listed writer Dalton Trumbo. With Laurence Olivier, Tony Curtis, Jean Simmons, Charles Laughton and Peter Ustinov. Ch. 56, 8 p.m. Color, 3 3/4 hours.
Interface. Rep. Shirley Chisholm (D-N.Y.) and Rep. Ronald Dellums (D-Calif.) assess the political impact of the Congressional black caucus. Ch. 2, 11 p.m.
Kentucky Derby. The 100th running. Ch. 7, 5 p.m. 1 hour.
Theater in America. Lorraine Hansberry's "To Be Young, Gifted and Black." Ch. 2, 8 p.m. 1/2 hour.
Curucu, Beast of the Amazon . Chances are that nobody has ever heard of this movie or would ever want to see it. The best alternative at this hour, unfortunately, is The Tonight Show with Roy Clark and Phyllis Newman. Ch. 5, 11:30 p.m. Color, 1 1/2 hours.
Meet the Press. Reporters Interview James D. St Clair, an employee of the U.S. government who earns $42,500 a year trying to keep the chief out of jail. Ch. 4, 2 p.m. 1/2 hour.
Golden Boy (1939). A Clifford Odets play about a boxer who feels he must give up the ring and devote himself to the violin. This is a sentiment that plagues many prize fighters. Ch. 38, 7:30 p.m. B/W, 1 1/2 hours.
Goldfinger. (1964). Sean Connery as 007. My brother saw it five times (Why I'll never know). Ch. 5, 8:30 p.m. Color, 2 hours.
Porgy and Bess (1959). Gershwin, Goldwin, Pearl Balley and Sammy Davis Jr. Ch. 5, 9 p.m. Color, 2 1/2 hours.
The Story of Pretty Boy Floyd (1974). Martin Sheen, who ably played Private Eddle Slovik on TV a couple of months ago, returns in this made-for-TV drama about the famous crook of the 1930s. Pretty Boy's real mother appears in a brief introduction. Ch. 5, 8:30 p.m. Color, 1 1/2 hours.