After seeing the modifications to the boiler required to accommodate a larger flywheel I opted to make an adapter for the sensor to be able to read the 21mm flywheel.
Meeting critical dimensions required time and care to make this little bracket. This plus the mod to the motor mount represents almost two hours time. The gap to the test strip is .035" not far from the ideal .030" and well within tolerances.
Now to sort out a correct tach tape.
Pete