If your Alli is not overfilled then I would check the size of the cooler tubes. I don't know what kinf of fan or coolers you are running. Be happy to look at it for you.
Is the TC locking? When the TC locks in High gear you should beable to feel it or see it on the tach.
If going up a hill, below high gear lock-up speed, then try it in T/H.
That might give you a better indication of what is going on.
The H2 is a whole different animals guys when it come to trans cooling. Untill I see how the cooler and fan setup is I will comment. Remember this is a transplant.