Brown & Williamson Tobacco Co. will sell off its Montclair, Malibu, Riviera, Crown's and Special 10's brands of cigarettes and its Bull Durham brand of chewing tobacco to Lorillard Tobacco Co. for an undisclosed sum. The Federal Trade Commission, which has to approve the deal, earlier required B&W parent B.A.T to divest Montclair and to offer the buyer its Tareyton brand as well as a condition of approval for its $1 billion acquisition of American Tobacco late last year. Lorillard isn't buying Tareyton. Montclair, the most heavily advertised of the brands, had been handled by Tatham Euro RSCG, Chicago. Avrett, Free & Ginsberg, New York, handles all Lorillard brands (except Newport, at Saatchi & Saatchi Advertising) and would be the likely beneficiary.