If your crank is cast, there is no factory flywheel for you that will correct the imbalance you have now. Factory stick cars and trucks would have forged cranks, even 400s. And that situation HAS to be corrected. Whether it feels bad or not, you can destroy and otherwise good engine in a few miles running it that far out of balance. IIRC, there was a Mopar Chassis Manual that had where to drill and how much to remove to make a factory nuetral convertor the proper weight for a cast crank. In terms or "ease", the aftermarket cast crank flywheel is probably it, if the $$ is available.