A spokesman for Hanson Trust said the British company has no plans to sweeten its $720-million offer to acquire SCM Corp. . . . Mass Merchandisers reported that the special meeting of its shareholders to vote on the previously reported merger with McKesson Corp. has been set for Sept. 24 . . . Coca-Cola said it is test marketing Minute Maid Orange Soda with 10% real orange juice in Washington . . . The Battery Street Enterprises unit of Levi Strauss & Co. reported that it plans to sell its Resistol Hats division to RHE Inc., a company formed by Irving Joel, for undisclosed terms . . . Joseph E. Seagram & Sons, a unit of Seagram Co., said it will acquire from Hudson's Bay Co. the share interest it doesn't already own of Hudson's Bay Distillers for undisclosed terms . . . The American Iron and Steel Institute reported that steel production for the week ended Aug. 24 rose to 1.623 million tons, an increase of 2.8% from the previous week.