SOUTHMARK <SM> SELLS NATIONAL HERITAGE STAKE National Heritage Inc, a unit of Southmark Corp, said it began an initial public offering of two mln shares of common stock at a price of 9.50 dlrs a share. All the shares are being offered by National Heritage, which will trade under symbol NHER on Nasdaq, through lead underwriter Drexel Burnham Lambert Inc. Proceeds will be used to increase working capital, complete renovations at leased facilities and repay certain debts to Southmark. After the offer, Southmark will retain about 82 pct of the 11 mln outstanding common shares of National Heritage, which operates 201 long-term nursing care facilities.