The J60 may or may not have points, some Belgian machines have points. If The J60 has got an electronic ignition module then it will also have a rev limiter built into the module that can be disabled by pulling a fuse which will either be on a fuse holder incorporated into the ignition coil (British Machines) or if a Belgian machine on a fuse holder adjacent to the coil.
The Rev counter is normally driven by a pickup mounted on the counter through which passes the ignition feed wire. The Rev counter was made by Smiths Industries and is now unobtainable, through age it loses accuracy and can also lose linearity. because of loss of magnetism and the hairsprings becoming weak, as well as friction through wear in the movement bearings.
It maybe repairable, in the end I gave up with mine and fitted a VDO rev counter with a sensor off the fan, The VDO rev counter also has a hours run meter.
The diesel model CVRT uses the same VDO rev counter using a Honeywell sensor mounted on the flywheel sensing the flywheel starter teeth. A suitable sensor pickup point on the petrol engine is also the flywheel starter teeth, were in not for inaccessibility a more ideal sensor pickup point would be the rear of the engine crank toothed belt drive which has less teeth per revolution.
Anyone doing a conversion to a VDO stepping motor rev counter needs to consider the design of the sensor and it's maximum pulse output, since with too many teeth on the pickup point some sensors cannot cope with the frequency. Some sensors require power and others do not. The other considerations are the clearance between the sensor and the tooth or bolt head it senses as well as the cost of the sensor (The VDO magnetic sensor is astronomical in price) The VDO stepping motor rev counter is the most versatile of rev counters, will cope with most types of sensor and can be calibrated in situ.
Diana.