The Conference Board's help-wanted advertising index (in which 1967 equals 100) rose to 140, a 3.2% increase over September's reading and that of October, 1984, the New York-based economic research group said. "The rise in want-ad volume in October brings the help-wanted index back to the level reached in July," Conference Board economist Kenneth Goldstein said. The survey measures the volume of classified advertising in 51 major newspapers across the country. Want-ad volume rose most sharply in New England with an 11.7% gain, the survey showed. Volume rose 2.2% in the Pacific region.