They're called "torque plates", and they're only necessary during the final cylinder honing, not the rebore job. Be sure the bolts holding the plates down engage the same number of threads in the block as the head bolts, or the whole operation is worthless. It does make a difference in the piston clearance when it's done correctly.
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!
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