The A440 transmission is a tough unit, our team has developed some interesting mods to increase transmission life and give it a nice tight feel. Our research has mainly concentrated on line pressure and torque converter lock-up control.
We rarely do this in kit form but would be happy to discuss a unit on an exchange basis.
Most of our modifications are done with a standard rebuild so it ;feels like it;s been rebuilt;. But for the hi-performance application we use heavy duty friction linings and increase the clamping force even more.