Web letterpress equipment is converted to offset lithographic equipment by modification of a driven letterpress impression cylinder to receive an offset blanket, thereby producing an offset blanket cylinder. A letterpress plate cylinder is modified to become an offset plate cylinder with accompanying offset inking and dampening equipment. In one embodiment a drive letterpress plate cylinder of a color hump is packed to become an offset impression cylinder cooperating with the offset blanket cylinder. In a second embodiment the letterpress plate cylinder of the color hump is modified to an offset color plate cylinder and a driven offset impression cylinder is added to cooperate with the offset blanket cylinder. In this manner at least two colors may be offset printed on one side of a web. When used in combination with similarly converted letterpress plate, impression and color hump plate cylinders, at least three colors may be offset printed on one side of a web or multiple colors printed on opposite sides thereof. The press tower is rewebbed to print with proper registration in the bight between the respective offset blanket cylinders and offset impression cylinders.