Fit it with a `proper big round RRPM/ERPM GAUGE......
The R22 was originally designed witht he leisure or personal business traveler in mind so those RRPM and ERPM gauges were probalby suitable for the purpose of that market segment and a key was going to give you the feel of your aero car.
what surprises me is that the R44 continued to follow the obvious R22 miscalibration. I hate it when the H300 battery voltage is more visible than the R22 RRPM. hard to learn doing autos when you have to resolve millimeters on the needle to get ahead of the aircraft.
I personally think that automotive ignition type switches have no place in the aviation industry.
I think a key should have authority to the engine start (if needed at all), but authority to engine stop belong to the mixture or fuel shut off valve
Certification wise, it seems that it is hard to implement incremental modfication or improvments to an established type.
Yet, the exception:
Airbus helicopter has on the AS350-EC125-H125 made 17 variants (+ 6 conversion kit avaiable)
blade size change, number os seats, dual hydraulic, FADEC, VEMD Avionics, Fuel tank .... it seems that only the center frame and the control rods have remained as designed 50 years ago.