GOOD MORNING: It’ll be either election eve or inauguration eve–for Showtime’s airing of Larry Gelbart’s “Mastergate.” The cast for this no-holds-barred version of his political play will boast: James Coburn, Nora Dunn, Paul Winfield, Burgess Meredith, Dennis Weaver, Darren McGavin, Pat Morita , William Hickey, Richard Kiley, Ed Begley Jr. and Ken Howard–all starting to work next week in a Pasadena courtroom, subbing for a Senate hearing room. Michael Engler, who directed the play in N.Y., dittos the TV’er. Charles Joffe is exec producer, David Jablons producer. … Hollywood has long admired the savoir-faire of French pix and converted them to English. Now Gerard Depardieu and Robert Duvall are readying for a Sept. 13 press confab at the Deauville film fest, where Depardieu tells his plans to French-film “Tomorrow,” in which Duvall starred back in 1972. The pic was screenplayed by Horton Foote, from a William Faulkner tale set in Mississippi circa 1910. Before heading to Deauville, Duvall talks his memories of the making of “Lonesome Dove” as a benefit for the MET theater, Aug. 29. Teleplay writer-producer Bill Wittliff is a special guest as well. … Nora Ephron, screenwriter-director of TriStar’s “Sleepless in Seattle,” set Rob Reiner to cameo as Tom Hanks’ business partner. You recall, Reiner directed “When Harry Met Sally,” also written by Ephron. Gary Foster, who produces the movie, which locations in Seattle, Baltimore and N.Y., says it’s kind of an homage to “An Affair to Remember.” Meg Ryan co-stars. … Ephron also set Sarah Trigger for the movie, although Trigger (Steve Martin’s teary g.f. in “Grand Canyon”) broke her leg and is in a cast. A “walking double” will be used for Sarah, most of whose scenes will be shot from the knees up. … Woody Allen, who yesterday filed for custody of two children he and Mia Farrow adopted and one they parented, has decided to title his TriStar movie “Husbands and Wives.” … MGM has retitled its Kathleen Turner-Dennis Quaid co-starrer “Cloak and Diaper” as “Undercover Blues.”RICHARD PRYOR helped “enormously,” revealed Margot Kidder, who ran up “hundreds of thousands” in medical and hospital bills in the past year and a half following the auto accident in Vancouver while she was shooting the “Nancy Drew” TV series for Nelvana. Kidder had to declare bankruptcy when the SAG wouldn’t pay her bills, she says, because her injuries were caused by “third-party negligence.” Kidder’s suing Nelvana. But what’s more important, Kidder is A-OK–back in Hollywood, sounding great, saying, “I have a new life and I’m able to run, work out in the gym as well. It’s finally over,” she says of the nightmare. And she’s ready to return to acting and directing. … Garfield High School was the location yesterday and again today for “Education First,” a two-hour Sept. 8 CBSpec with an all-star cast, hosted by Sinbad. Yesterday, Arnold Schwarzenegger taped his seg in the school gym. Others who have appeared (or will) include Whoopi Goldberg, Tony Danza, Lily Tomlin, Danny De Vito, Rhea Perlman, Woody Harrelson, Debbie Allen and Jaime Escalante, and at a show at Garfield tonight, Olympic gold medal winner Oscar de la Hoya appears with Sinbad , Paul Rodriguez, BeBe & CeCe Winans, Salt N Pepa, Wilson Phillips and the City Kids. Don Mischer produces with exec producers Jeff Wald, Lynda Guber, Carole Isenberg, Paul Rodriguez and Propaganda Films. … Bud Schaetzle, who produced NBC’s January hit spec “This Is Garth Brooks,” will exec produce NBC’s “Michael Bolton Special” Aug. 26-27 at the SRO Arie Crown theater in Chi. … When Hallmark boss Don Hall heard that Emmy-nominated Joe Sargent, on location outside Kansas City on “Sarah, Plain and Tall II,” wasn’t going to be able to attend the awards, where “Miss Rose White” has 10 nominations, Hall arranged for a private jet to wing Sargent out–and back right after the ceremony. GEENA DAVIS and ex-husband Jeff Goldblum were dining at the Nowhere Café. … Nicky Blair, who played Shorty Farnsworth in “Viva Las Vegas” (1964) with Elvis and Ann-Margret, invited A-M and director George Sidney to view the movie with him toasting Presley on Sunday. Tomorrow, George Sidney lunches the L.A. Crix at his home as they toast him. … Trumps eatery closes its doors Sept. 5, and it’s anticipated the Columbia Bar & Grill will reopen it as a seafoodery. … Sunday, the William Morris Agency hosts a day at the Ringling Bros. and Barnum & Bailey circus for 400 staffers and their families Jennifer and Doug McHenry (Jackson/McHenry Prods.) welcomed daughter Lyric Leigh Aug. 6 at Cedars-Sinai. … Former “Days of Our Lives” co-star Maree Cheatham signed with CBS for a half-season on “Knots Landing” as bad girl Mary Robeson. What happens to her in the other half-season? Gregory Harrison plays a millionaire killer–with a penchant for videotaping his crimes–in “Split Images,” syndie’d by TriStar. Zev Braun produces and Sheldon Larry directs the Pete Hamill script. … Melody Thomas Scott’s Save the Earth Foundation fundraiser raised $52,000 at the Bel-Air Hotel. … Ann Blyth and Bill Hayes will play the Rainbow & Stars Oct. 27-Nov. 2. …1 Rip Taylor, back from a month’s gig at the Dunes in Vegas, found a $410 bill from Pavilions “for groceries during the time I was away,” says Rip. Seems his bill got mixed up with another Taylor–Liz.