What is the trans doing that makes you unhappy with it? Was there a modification done that after the trans wasn't where you wanted it to be?
Do you have a pressure gauge that can be hooked up to see what the tv valve is doing? If the pump isn't supplying good pressure the trans won't shift well. Without good pressure clutches slip.
Mike and Jake are excellent choices. I'm sure both have forgotten more than I know about transmissions.
I made a new thread in the transmission section, I listed the pressures
http://www.ihadav8.com/forum/index.php?topic=4849.0