‘N INK Despite buzz that interest in bubblegum pop may be waning, publishers are still hoping to score with big-ticket teen books. A Mother’s Gift, a new young-adult novel from 19-year-old Britney Spears and her mother, Lynne, hit stores this week. The pop star’s publisher, Delacorte Press, which released a first printing of 500,000 copies, is betting that fans will flock as heartily to Britney’s fiction debut as they did to her nonfiction. (Britney Spears’ Heart to Heart, a memoir written by the mother-daughter team, has 189,000 copies in print after six pressruns.) The novel’s main character may sound familiar — it’s golden-haired Holly Faye Lovell, a chaste 14-year-old from a small Southern town who dreams of pop stardom. Not to be outdone by his good friend, ‘N Sync heartthrob Justin Timberlake is tossing his own bejeweled jean jacket into the literary ring. Vigliano Associates has been circulating a proposal among New York publishers for a sports thriller to be penned by the 20-year-old song and dance sensation called Crossover Dribble. ”The character is a white Michael Jordan — a basketball phenomenon,” says an editor who passed on the book. The hero’s name? Justin Woodriver. (Wood-river. Timber-lake. Get it? Of course you do.) Will he enjoy the same success as the Spears duo? ”His audience is girls, and sports thrillers — which are a tough sell no matter how well they’re written — are a boys’ market,” says another editor (who also passed).