This page outlines the pump modification to increase line pressure to the converter. Start with step A and finish with step E. Notes indicate the changes that dial this in to the late model 4R100 converter.
This picture doesn't really show what I wanted. But it might help. This is the the side view of a 5R converter in a 4R100. The converter IS FULLY ENGAGED. This is the shipping plate for a 4R100 which should fit flat against the trans case. The converter should then be pulled forward about a 1/4 inch