[RCW]

That is a tough question.

I used to do the governor mod all the time, then ended up walking for more than two days out of the brush and swamps of Alberta during moose season because of a blown engine.

I decided I never wanted to walk that far again, so now run it stock.

If you run correct and clean oils, keep the valves adjusted, do not let the clutches get out of tolerance, run a belt that is within the specified tolerances, and never exceed the maximum designed engine red line, it should be fine. But, that is what I was doing too!

 

[RCW]

I do not have the engine rating rpm's at my fingertips, but as long as you stay below the maximum rated rpm you should be OK. No guarantees though, as you are putting additional stress on the clutches and if they are not kept serviced you can snap a crankshaft or simply cause the drive clutch to explode.