My last trans was built by A&A. It was the only trans I had with the vent moved to the rear, and the only trans I had that leaked from a vent. I ended up running a nylon tube up to the dipstick to prevent the leak from oiling down the car on a heavy pass. Hardened shafts-so no governor. Just didn't work for my combo. The tube solved the problem so I guess it turned out fine in the end.
I could see how a drilled drum would cause an issue with the pump located vent. Maybe they vent the drum differently now so relocation isn't needed?