360 balance ?s

The weights will be opposite each other. Not possible to install a flex plate backward. Since the weight on the converter is located between the mounting pads it will be located in one of the recesses of the flexplate. It is a stock flexplate isn't it? If it is it needs a weighted converter, if it's a B&M or TCI flex plate it doesn't need a weighted verter. If it is a stock flexplate I wonder if it has the right weight on the verter cause Mopar had at least 4 different weighted converters that I know of. Had a buddy with a 440 in a Challenger that had a vibration like you describe and it turned out a very highly regarded trans. shop in PA had put a 360 converter behind it when it should have not had a weight at all cause it was a steel crank engine.