Coast-to-Coast Ambitions Although U.S. Bancorp is no longer thought to be a candidate, companies that are identified as possible marriage partners for KeyCorp include Norwest Corp. and First Bank System Inc., both based in Minneapolis, and Banc One Corp., based in Columbus, Ohio. Merging with any of these banking outfits would satisfy Mr. Riley's ambition to build a coast-to-coast banking franchise and presumably solve his succession problem. In the case of U.S. Bancorp, for instance, it had tentatively been agreed that Mr. Riley would oversee the merged company for a few years, then turn over the reins to Roger L. Breezley, U.S. Bancorp's 54-year-old chief executive. Although a union with U.S. Bancorp would have been virtually a merger of equals, the headquarters of the surviving institution was to be in Portland. Contenders The chief executives of KeyCorp's most likely partners also are comparatively youthful.