I believe Levelten itself sells a revalved valve body (larger orifices, stiffer springs, etc). Basically you send them yours and they turn it around in a few days (you may need to double check that).
Also, I highly recommend B&M oil/trans. fluid coolers. They make a "stacked plate" unit which is stronger than the tube and fin style found on other heat exchangers (coolers). A 4" x 6" unit will run you about $45. Be sure to run it in parallel with the radiator unit else you won't benefit as much.
I had one in my Nissan and I used to get some slight slipping after driving for hours in the summer heat. The cooler virtually elimintated the slippage. Shifts were firmer, etc.
Also, go with synth. ATF (I believe Red Line makes synth. fluid).
I'm sure others can offer suggestions....