That's not really how it works. The first step is to weight match all the pistons and each end of the rods. Since he used aftermarket racing pistons and rods, they were likely already pretty close to matched out of the box. I'd be surprised if they varied by more than a gram. Once the weights of the rotating and reciprocating components were equalized, a bobweight was calculated, and that's what gets attached to each throw of the crank when it gets spun on the balancing machine.I figured the person balancing would have weighed and marked what bore each piston went into according to weight.