The proposed new cable network Turner Classic Movies has announced its start date as April 14, amid rumors that Turner will end up taking over the American Movie Classics cable channel before the year is out.Sources say behind-the-scenes maneuvering could result in Tele-Communications Inc.’s Liberty Media Corp., which owns 50% of AMC, ponying up about $ 200 million to buy out the interests of Cablevision Systems and NBC, which share the other 50%. But the $ 200 million would really be coming out of Ted Turner’s pocket, and Turner would take over as owner and operator of AMC, avoiding future bidding wars for movie-library product. TCI would sign off on the deal because it owns 22.3% of Turner’s networks, including TCM, which would benefit from not having to go head-to-head with AMC for classic oldies. Other sources say, however, that Cablevision Systems doesn’t want to sell AMC and is trying, with NBC, to put together the financing to buy out Liberty Media’s 50% bythe Sept. 16 deadline. Despite all of these negotiations swirling around it, TCM officials said the April 14 launch date commemorates the “exact centennial anniversary date of the first public presentation of motion pictures” at the site of a converted shoe store in Manhattan. TCM also said it will join with its sister Turner Entertainment Co. to help finance the restoration of 250 movies in the library it owns, consisting of more than 3,000 pictures from the vaults of MGM, RKO and pre-1948 Warner Bros. The restored movies will get heavy promotion when they premiere on TCM in a weekly showcase. Among the titles Turner will restore are “National Velvet” ( 1944), “On the Town” (1949), Bette Davis’ “Cabin in the Cotton” (1932) and the 1930 John Barrymore version of “Moby Dick.” Besides the Turner library, TCM will draw on the 300 Paramount titles produced from 1948 through the mid ’80s that it has bought for an exclusive window. Brad Siegel, executive VP of TNT and the point man for TCM, said more movie-output deals are in the works.