With my first LPG Honda motor ,I disconnected the governor and connected up a Tachometer and adjusted the rpm manually.
You could just set the throttle control so the motor can't over rev but it's not that good for cutting longer grass as the motor wants to stall more without the governor, the mower works well if the grass isn't too long without a governor.
I seem to remember you doing a similar thing on ride on mowers when the governor isn't working ,you just disconnect the governor linkage and set the throttle so it's not over revving.
Fitting a linkage or butterfly stop would stop the engine over revving.
