The writing pair of Steven Naifeh and Gregory White Smith won a Pulitzer Prize for their Jackson Pollock: An American Saga, which became the basis for the current Ed Harris movie, nominated for an Academy Award. Now they are turning their sights on a painter considerably more written about, Vincent Van Gogh, aiming to do what publisher Random House hopes will be a definitive biography (take that, Irving Stone!). Senior editor Katie Hall preempted North American rights only from agent Mel Berger at William Morris and tentatively plans to publish four years from now. The authors, who have done 15 books together, are both Harvard Law School alumnae, and Naifeh went on to the Fogg Art Museum. The pair say they will incorporate recently discovered letters that were not available to previous biographers.