Governors were mostly designed to protect the engine from over-revving in the lower gears on big rigs that spent a lot of time pulling in something other than top gear. Babbit-rod engines like the 216's and early 235's had a bad habit of hammering the rod bearing material out if they were over-wound for long periods of time. The top speed limit was just an added advantage for fleet trucks.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!