Rack and Pinion: Increasing Linear Movement of Rack

The linear travel of a rack in a rack and pinion is always going to be the radians of rotation multiplied by the radius of the pinion it meshes with, less any initial backlash. Otherwise the teeth on the rack would need to pass through the teeth of the pinion. You could add an epicyclic gear train before the pinion to increase the total revs of your rack-pinion compared to your new input.