He has probably published more con serva tive books than anyone else, but when Alfred Regnery decided to write his take on the politi cal movement, he shopped it to a publishing house other than his Regnery Publish ing. "You can't have your name on the top and the bottom of the book's spine," he demurs. So come January, Upstream: The Ascendance of American Conservatism will be published by Simon & Schuster. Simon's Mary Matalin raves that it will be a wake-up call for conservatives. For Regnery, going to Simon was more than just ducking what some might have seen as simple self-promotion. He says the mainstream publishing house's purchase of Upstream proves the importance of the conservative movement. "Ten years ago they would have told me: 'Get out of here.' "