HELENA, Mont.—The leader of a talc-mill union locked out for almost three months last year is now the president of the Montana AFL-CIO. Randy Tocci, president of International Brotherhood of Boilermakers Local D-239 at Imerys Talc in Three Forks, took office this month after being elected head of the 44,000-member state labor federation in June. He ran unopposed and will serve a two-year term. Imerys, a French-owned talc company, locked out about 35 workers last August after they rejected a contract that would have eliminated seniority, overtime pay, and retiree health insurance. The union eventually won a deal that preserved most of