You are going to have to pull the trans to relocate the vent, part of relocating the vent is the block the one in the pump housing, you can't do that with it in the car.

Did you do anything to modify the the front drum so it expels more fluid when venting? Is the plastic baffle for the vent cover intact inside the trans ? stock drum or a billet drum with a larger piston that requires the vent to be modified ?

running up my post count some more .