28 oz, 50 oz, or neutral ??
You'll need to match balance it to a known imbalanced flywheel at least.
It's a common prob with windsors - unfortunately
We premachine the imbalance to our flywheels but recomend that they be balanced with the rotating assy when building the motor - if thats too hard, at least match balance it with the flywheel or flex plate that came with that motor