Snook's 85 makes me jealous
I can take a picture of my 85's vacuum system set up for you if you need me too. It's all original (including the emissions).
See if you can figure out what was disconnected.
Do your door locks and HVAC system work? I'm guessing that the PO may have deleted it from the engine bay because of leaks. If you repaired those leaks the proper amount of vacuum would be applied to your transmission and it will begin to shift properly.