I got the new valve body and installed it yesterday.
It runs beautifully in the 50 or som miles I’ve put on it. It was pretty cold (-20C) so I’m not sure if it got hot enough in the 50 miles for a problem to crop up on not.
I’m hoping this is the last major repair I have to do on this thing.
I did manage to find a used complete (less torque converter) trans at a wrecker which I bought for $130. I plan to keep this in my back pocket just in case.