There are many performance AOD trannys out there. This company has the best of the best.
The 86 to 93 AOD has a weird shift pattern. If you try to manually shift it, it goes from 1st to 3rd. You can force it manually by immediately pulling back on the shifter into low as it shifts out of low. Sounds weird, right! It is so counter intuited to normal shifting it scares me! Lentech offers a way improved valve body that includes a rocker switch to shift in an out of OD. And then changes the AOD to shift like a C4. And they also offer a trans brake and reverse valve body if you are so inclined. If you like an auto their stuff is bomb proof. I "reprogramed my stock shifter to force you to push the button to go into neutral. This allows manual shifting without fear of hitting neutral.
Another company is:
https://transmissioncenter.net/
They offer complete packages for Mustangs. Pretty sure they will work for Cougars. I have pics of my reprogrammed shifter and have used both companies and install myself. I prefer Lentech because of the reprogramed valve body in a normal pattern vice reverse. But PATCO trannys are also bomb proof. The AOD’s can withstand as much HP as any tranny out there. I prefer a manual tranny and just installed a TKO 600 5 speed from Modern Driveline in my 67 Mustang. It is the shit!! Either AOD or 5 speed performance 5 speed will eat up around the same $4k to $5k based on accessories.
I can step you through you purchase. The guys at a Lentech and Modern Driveline are the best!! I have a shop and run customer cars through and have installed all of these products. I also rebuild top loaders if need be.
Rob