i think in park it should be 75 to 90 psi. it has been almost 10 years since i messed around with this, but i remember backing it off 1 click at a time and noting how much it took to press on the tv cable and watching the needle not move. this was an "ah ha!" moment from when i did my first overdrive (200-4r) swap behind a 305 2bbl and used the TH350 kick down stud. trans was overhauled and only lasted about 2 years of daily driving duties .