Tranny huh? Well based on my experience over the last few years with tranny shops, if you can rebuild it yourself with the best parts out there with super attention to detail or get a performance one installed. Have not tried a performance one myself yet so no reviews on that yet. But between TCI, B&M and Monster there has got to be a good one there somewhere. I myself want to self build a 4l80 to swap in place of the 4l60e but don't have the funds to do so right now. If you can do a performance on expect them to range from $1900-$300 depending on options of parts used. At a bare minimum try to get a gm remanned one. Take as much time as needed to research every option and maker to do what is in your best interest. Ask as many questions as possible and even if it means taking a long time. The cost of a tranny equals the same on choosing a new engine. They are an investment and should not be taken lightly.
Feel free to ask anything you want as much as you want. I am sure we will learn something we did not know from you as well.