By the time you get to a straight line rack, the teeth to mesh with a normal involute gear approach just straight sided shapes. The 135-rack cutter in the set will work for the rack as well as any gear over 135 teeth. For the pinion, you would need the cutter that includes the number of teeth you need. For the smallest number of teeth, the teeth are shaped for the tighter curve around the gear, the more teeth, the more the shape squeezes in a bit.
Not sure if that helps?