5.9 Weighted Flexplate
If I understand correctly the converter you are wanting to use in the 727 is weighted. But being you have a 5.9 Magnum engine, you would need the converter weight to be correct for that unique balance engine and then use a neutral flexplate. For simplicity Id knock the weight off of the converter and use the Magnum Mopar weighted flexplate listed above. You obviously wouldnt want both the converter and flexplate weighted.
But if the 727 converter you are using is neutral, then a B&M 10236 weighted flexplate is the one you want.