TorqueFlite 727 904 Cut Bellhousing for Converter Bolt Access

And according to multiple people in this thread who have utilized the notch modification for their specific 727/904 applications, the bellhousings don't crack and converter seals don't get destroyed from grit, especially if they built a cover for the notch.
....and they won't crack as long as the cut is a nice job like you did that removes all of the sharp edges.