A couple of years ago I was out for a test ride with my new 440 engine and had a problem with a leaking front seal on my 727. I could drive at the highway without any problems but if I stopped and raised the rpm (Turbo Action J-conv) for a testrun it just pissed trans fluid out of the front seal.
After some investigation I found that the front cooling line was bent more than it normally is (stock cooling lines). I just bent it back with my hands and went out for another test and the problem was gone.

I'm not a 727 guru so correct me if I'm wrong, if you plug the front cooling channel (= the output to the cooler), the oil flow from the converter will be to big so the front seal could start leaking, you will have the same problem if the front bushing/bearing have moved and restrict the channel for the oil flow.