I have both ATI and TCI adapter kits, and they use a special flywheel that already has the Mopar crank pattern on it. It is drilled for the GM converter. Both have a billet retainer ring that goes on the outside of the crank hub for the converter to rest in.

Make sure you have the converter properly centered when using the BBM bellhousing on the case. I know of some people who had troubles with the ATI setup where the converter was slightly off-center. They had to use slightly offset dowels to correct everything.