For the governor you need to check the static adjustment. Basically you rotate the throttle butterfly to wide open while watching the governor arm and note the direction to moves. Then you loosen the retainer on the arm and continue rotating the cross shaft in the same direction until it stops. At which time you lock the retainer back in place. These cross shafts do get out of adjustment anytime one loosens the retainer. Once you get this adjusted try running the engine if it still accelerate uncontrollably check to see you are get any push back from the governor. If none then the governor has failed.
As for testing the alternator (stator) output there is good list of voltages that you should expect in the Briggs Repairman's Handbook manual for the pre-1981 engines. Note this file is about 21 megs.
Briggs Repairman Handbook 1919-1981
