ALLEGHENY <AG> PREFERED SHAREHOLDERS FILE SUIT Allegheny International Inc, which has agreed to a merge with a jointly-formed First Boston Inc affiliate in a deal worth 500 mn dlrs, said shareholders of its preferred stock have filed a class action complaint against the company. The complaint alleges, among other things, that the company and its board agreed to pay First Boston an illegal seven mln dlr topping fee if it received a higher offer for the company prior to the buyout. The suit contends that this fee hampers Allegheny's ability to attract other offers or take other actions that would benefit holders of preferred stock. The complaint also alleges federal securities laws violations and breach of fiduciary duty. The suit requests an injunction against proceeding with the pending offer being made by Sunter Acquisition to acquire Allegheny. Sunter Acquisition Corp and Sunter Holdings Corp were formed by First Boston and Allegheny. Allegheny said it and the Sunter concerns intend to vigorously defend the complaint's charges. The complaints were filed by Robert Moss and other parties who are believed to own about 230,000 shares of Allegheny's preferred stock.