valve bodies are easy to change after you drop the pan.
just 14, 1/4" bolts [7/16" head"], and the E clip removed from the park rod. [unless you elect to leave the rod attached, and move the driveshaft around so the ball on the end of the park rod pulls through the slot on the tailshaft "park gear"]
don't forget to remove the NSS, and the kick down and gear selector levers before you start.
i think the trans-go TF-2 instruction pdf has been posted here before. the pictures will show you what needs done.
as for finding a stock valve body, check any transmission repair shops near you. you might get lucky. or post a want add in the proper transmission forum here.
when you say the kick down arm is "screwed all the way back", do you mean it's as short as it can get ?
