So deep in tranny thoughts as you are is the detent spring still there and good? How about the torque on the helical gear on the out put shaft? (Looking for shaft movement) Just mentioning these things so you can keep a eye on things as you split her open.
Nothing is out of place and all gears engage/disengage as they should.
The the tall dogs on input 4th are slightly rounded but there is still roughly 70% face to face with 5th input dogs. I will see if i can snap some close-ups