It can be done, Rock. The first step is to determine the degree sweep of your speedometer so we can start at 0 and go to 120mph following the same sweep. I have a feeling we'd need to use the 0 to 200 mph speedometer. Then we have to do some surgery/modification. Hopefully you can find what I did. Actually I did the same thing for a GPS speedometer and also for the T5 output pulse speedometer made at that time by SpeedHut. Both work fine...the GPS is easier and requires no calibration once you have it set correctly to 0 and 80 or 120 or whatever your top speed will be.
