So there really are only six areas that can leak in the bell housing. Having eliminated the converter.
1) converter hub lip seal. Been replaced along with bushing.
2) interference fit of outside of that seal. Been replaced by two different people.
3) o-ring on perimeter of pump housing. Hasn't been checked yet.
4) pump housing bolts. No rubber washers? Don't know.
5) vent puking. Fluid level has been check in neutral while hot.
6) cracked case. Unknown.

Where in these six areas does the pressure of, or amount of fluid increase when the converter is charged?
Don't think it is the o-ring because I don't think it see's more pressure when the converter is charged. Unless line presure is leaking by the paper gasket and then the o ring. But line pressure is always present there.