Well, that kills that thought. I know certain MT-82's have been reported to not liking to be shifted at 7K+ rpms. Maybe time for a Tremec swap with some other goodies? I've had this site on hand through my research planning for a Coyote purchase at some point- http://moderndriveline.com/index.html
One of the negatives I've read from the Tremec swap is that some are not a smooth at the MT, and the rear gear ratio can have an effect on it as well since the 5.0 needs to keep the rpms up during shifts. Seems like the 6060 or T56 might work with some tweaks. Then again it's just opinions...