Time for 727 rebuild.

That's one thing I don't know is what has been done to it before I bought it. It shifts pretty well right now. I am maybe thinking of having the local transmission shop look at valve body to sort it out.
first things first don't be scared of that transmission whatsoever it's so simple it's not even funny. If there's something in that valve body it's easy to take off and just sit on your bench and clean out. But the real deal it's just completely rebuilding the transmission with a simple rebuild kit. Then you're off and gone with a new transmission that you probably won't worry about for the rest of the time you own the car....