The Briggs model 140000 motor started with a HP rating of 5 3/4hp, and was upgraded to 6hp when the coil/flywheel polarity was changed. This caused a lot of confusion when ordering parts. Information on this motor was left out of many Briggs manuals.
This ad states the motor was "Tecumseh 6-HP all aluminum motor". You may notice in the 'EQUIPMENT AVAILABLE'... "Optional 8 1/2 HORSEPOWER Gov't Rated 2 CYLINDER MOTOR (Special Order Only)". I wish I had more information on that option.