Those engines were governed for a reason. One over-rev and you'll have a good boat anchor. The W-head engines try to swallow valves above 5500 RPM, so put a tach on it and watch out about letting it wind up in the lower gears. I remember those engines well from back in the late 50's/early 60's. 348's had the same problem.
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!