Ford, Carnegie, Mellon and Rockefeller are respectable enough names in the realms of foundations, but in the minds of most people concerned with prehistoric preservation, city planning and the quality of life in New York City, they don't hold a candle to Kaplan. The J.M Kaplan Fund, which assets of roughly $120 million- an amount that the Ford Foundation would consider a rounding error- has for years been the first stop for those seeking grants to save buildings, support cultural institutions, restore landmarks and find innovative ways of creating housing in New York.