When the pressure plate is manufactured or reconditioned, it's balanced as part of the process. Ditto for the flywheel. At the normal RPM range a street engine is likely to run, extra balancing isn't necessary. If you're planning to rev one into the 6K RPM range or above, it might be a good idea to do some more precise balancing, but the engine is going to need some detail work to approach that speed.
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
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