The 2 7/8" stroke 289 Fords that Red Farmer raced would turn 8K all day- - - - -and he did it for decades with dozens of engines. The only limiting factor on my 250 cubic inch "305" was a restrictive carburetor. RPM is simply determined by efficient airflow, proper cam profile, and plenty of valve spring. A circle track engine with 500 miles on it is about as rare as a chicken with lips- - - - -they wear out or blow up before then.
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!