At the risk of being repetitive- - - - -you have plenty of room to install a clutch fan. Just eliminate the spacer. If the centering button enters the fan hub at all, even 1/8", it will do its job. The BOLTS hold the fan on, not the centering button.

NEVER, EVER, CUT A FAN BLADE FOR ANY REASON! IT'S DEADLY DANGEROUS!

You could also drill and tap the centering button for a bolt and a flat washer. A little red LocTite will make the spacer and the fan blade a single piece installation.
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!