Eventual I got an old 4L80E transmission I had laying around rebuilt by a local speed shop out here. I kept the automatic valve body but I was told this thing should still hold some serious power.
As I have mention before, make sure you mock up and check EVERYTHING!
Also remember, never draw a transmission to a motor with the bell housing bolts. If something isn't right you can snap off parts of the trans casting or whip out a trust bearing inside the transmission.
When I went to bolt the trans to the motor there was a little binding. I can't recall what exactly was going on but I had to change out some parts do to interference with flywheel and the torque converter.
Another issue I had with the trans was the sickout of the torque converter. The puck in the center of the torque converter need to stick out into the back of the crank a certain amount when the torque converter is pulled up to the flex plate.
At first there wasn't enough stick out. This is in revers, as we are looking here at the impression left by the TC puck in some play dough.
I had to send the TC back to the trans shop where they added some length. Even the pros can't know every potential combo out there and can make mistakes. cover your ass.
This was what the proper amount looked like.