Looking for Info / Specs on Obsolete Mopar Piston

In response to doubts in previous post referring to "overbalance"--when the amount used on the bob weight is calculated at 51% or 52% rather than the standard 50%. Some believe for very high RPM operations it enhances horsepower or balance (something to that effect).
Ah, that makes all the sense in the world; it works out to around 51% in this case. That seems appropriate for a circle track engine, but I can't say if 51 vs 50% is going to show vibrations very badly on the street at low RPM, or not; I just always assume that the standard 50% factor is used for a good reason.