Betty Thomas is negotiating to direct a film based on the most unusual wagering premise since “Indecent Proposal.” Fox Searchlight and Thomas are in talks to start production by June on a comedy based on the true story of Brian Zembic, a professional gambler who took a $100,000 wager to get centerfold-sized breast implants and kept them for a year.Though it seems unusual for her to be moving from Sandra Bullock in “28 Days” to the man with 38Cs, Thomas might be the perfect director for such a quirky story, since she has found hit movie material in Howard Stern’s love life in “Private Parts” and the bigscreen sendup of the TV series “The Brady Bunch.” She sparked to the script last week and hopes to do what Barry Levinson did when he set aside his big-budget projects to direct “Wag the Dog” in a down and dirty low-budget manner. Thomas expected to next direct New Line’s adaptation of the Peter Lefcourt novel “The Dreyfuss Affair” about a romance between a shortstop and second baseman. But if talks work out, Thomas and Jenno Topping’s Tall Trees Prods. will move right into the Zembic tale, which was developed by producer David Friendly, the Fox-based producer of the upcoming Martin Lawrence comedy “Big Momma’s House.” Thomas and Topping will join Friendly and his exec David Higgins as producers. Friendly has worked with Thomas before, as he, John Davis and Joseph Singer produced the Thomas-directed hit remake “Dr. Dolittle.” The real Zembic is a charming and charismatic professional gambler who will bet on nearly anything for money. That included a $30,000 wager that he would live in a friend’s bathroom for 30 days without leaving. Despite the bettor’s clever strategy of sending over his burly friends to use the facilities, Zembic would not relent, leaving him flush with $15,000 when his friend settled after 15 days. That was nothing compared to the bet he accepted to get 38C cup breasts. Getting the breasts was easy, since Zembic beat his plastic surgeon out of the fee in a backgammon bet. Being saddled with them was another matter, though one that proved a pleasant surprise. Zembic expected to be holed up for a year hiding his new assets, but instead found that women liked his endowments and his sex life improved. Zembic won the bet, and hasn’t yet gotten his breasts taken out yet. Friendly and Higgins corralled life rights to Zembic and conscripted novelist Tim Sandlin to build a comedy around the character. The film’s far from a docu, but rather focuses on a prodigious bettor and how the breasts affect his attempt to land a woman way over his head. The guy also gets to experience what it’s like to be on the receiving end of the gawking to which well-endowed women are subjected. The Searchlight project is being fast-tracked by prexy Peter Rice and is being shepherded by Joe Pichirallo. Thomas is repped by CAA. FOX GETS CLOSER TO BROADWAY: Screenwriter Robbie Fox, who co-wrote with Mike Myers “So I Married An Axe Murderer” and is currently writing three studio comedies, has finally gotten his dream project off the ground. It’s to get his stage musical to Broadway. Fox wrote the book for “The Gift,” a musical that revolves around five college pals who are disillusioned by how their lives are turning out. Their fates are changed during a bachelor party encounter with a prostitute, who may be an angel. With a rock score written by Fox’s cousin Steve Fox, a Sony Music-based songwriter, “The Gift” has suddenly taken off. It’s booked for a six-week run at L.A.’s Tiffany Theater, beginning July 15, and a deal has just been closed for Andy Fickman to direct. Fickman just won the L.A. Drama Critics Circle best-director award for “Reefer Madness,” which hatched in L.A. and is headed for Broadway in the fall. The musical will be choreographed by Paula Abdul, who worked on “Reefer Madness,” and it’s now being cast by Nancy Nayor, the former head of casting at U, who recently cast “The Whole Nine Yards” and “Road Trip.” Though the musical is just getting started, a soundtrack deal has already been struck with Geffen Records, which wants to make a video. The play’s produced by Craig Baumgarten (who manages Fox), Adam Merims, Merv Adelson, Geffen Records prexy Jordan Schur and Interscope Records marketing head Steve Berman. Fox hardly qualifies as an overnight success. Love of the musical comes from his father, Charles, the Grammy-winning songwriter whose credits include “Killing Me Softly With His Song.” Despite that pedigree, Fox has endured years of false starts with “The Gift.” “I’ve been like Ahab, chasing this show for over four years, and banging my head against the wall each time someone said do it as a movie,” said Fox. “This show is the culmination of everything I’ve been writing and living the last five years, as I and my friends hit 35 and have our version of a midlife crisis. It’s the point where childhood ends, they have the house, the kids and the career and wonder when it’s going to get fun. It’s when you realize your parents lied to you all those years, when they said that if you worked hard you’ll be happy, and that they’ll be there to catch you if you fall. And either your dreams don’t come true or they don’t feel so good if they did.” It’s a theme that has relevance to the pics he’s writing, “Twice Upon a Time” at Fox, and “Business or Pleasure” and “Sex, Drugs & Rock N’ Roll” at Touchstone. Well, maybe not the last, which is about a band on the road and is being produced by Kiss’s Gene Simmons, who still has the stamina of a teenager. Fox observed this after spending a week on the road with the band, and watching Simmons get chased by gorgeous and voluptuous groupies even in Anchorage. “Gene told me, ‘I’m not that talented a man, but at the end of the day, your children buy my album and your wife will sleep with me.’ ” Fox’s hope is to be on Broadway shortly, and then make a screen deal for his musical. But he’s hardly smug; in fact, he needs to end the interview because he’s cutting a short film he made as a favor to one of his backers, Adelson, who will use it in a presentation to the heads of the multitude of dot-coms he owns.