You are using a mildly lighter piston, and the same heavy rod, but you reduced the counterweight by turning it down on a lathe. Counterweights that were already too light and require a heavy balancer and weight on the convertor. If you had posted earlier, I would have said get Brandon's. After balancing, it IS cheaper than using even a factory forged crank. You will need Mallory metal added to the cast crank to get it internally balanced.