727 problems, opinions wanted...

I had a 68 Charger with a 727 and a 2800 stall Mopar converter. It would take some revs to get the car to move in reverse after sitting over night. I drove it for years with it doing this. Putting it in neutral would help it build up and it wouldn't rev up to start to move.

I would do what 70duster440 said and go from there.