I take it that you simply disabled the operator presence control? (The brake handle that you have to hold in order for the engine to run) That system also incorporates the ignition kill... what are you doing for a kill switch, especially in case of emergency stops?
For the test I simply removed the cable from the bracket and zip tied the lever in the 'run' position. For a permanent solution I am going to run a throttle cable to the governor arm for engine speed control. When idled all the way down it will stall the engine. The throttle will be bolted to a clamp that I can secure to the hand rail on the fender of my tractor.