Software Publishing Corp, Santa Clara now thinks it has found a buyer for its Superbase clone of the dBase personal computer relational database for Windows, in the shape of Computer Concepts Corp, Bohemia, New York-based developer of graphics and printing software. Computer Concepts has signed a letter intent to buy the Superbase product line and related assets; terms and conditions were not disclosed and the pair say there can be no assurance that the negotiations will result in a final agreement.