HARCOURT <HBJ> DEBENTURES MAY TRIGGER SUIT Holders of convertible subordinated debentures of Harcourt Brace Jovanovich Inc threatened to sue the company if they do not get more information about how their investment will be affected by the company's proposed recapitalization plan. The holders, none of whom was willing to be identified, said although Harcourt has urged that they convert their shares to common stock by the June eight record date for a special dividend, they were unable to determine if it might be better for them to continue holding the debentures. "There are rumors that various houses will bring litigation if we don't get answers," said a Wall Street source. Officials of Harcourt declined to comment, citing a suit brought by British publisher Robert Maxwell whose has been trying to acquire Harcourt. Executives of First Boston Inc, Harcourt's financial adviser, did not return a telephone call seeking comment. When it announced its recapitalization May 26 Harcourt advised holders of the 6-3/8 pct convertible subordinated debentures due 2011 to convert into common by the June eight record date for the company's special dividend. Harcourt's special dividend pays 40 dlrs per share in cash plus a security worth 10 dlrs. Holders would also retain stock in the recapitalized firm. The debentures had been convertible at 34 dlrs per share. Harcourt's May 26 announcement said the conversion price would be adjusted according to the indenture covering the securities. Arbitrageurs said the conversion formula yielded a "negative number" and thus they needed further information from the company.