You can go a bit further if you wish. When you have the pan all buttoned up you can disconnect the line from the cooler (rad) and have it empty into a clear jug. Add a little oil at a time and run for short periods in neutral. This will attempt to cleanse the remainder of the transmission oil. You can watch your progress in the clear jug. Keep the running periods short so the transmission does not run dry.
And yes, be sure to re-adjust both bands. I usually make them slightly tighter than spec, especially if an older hi miler. You can double check the clearance with a feeler gauge, but I don't have that info. at hand at the moment. Could have been in Carl H. Monroes transmission book on 727's
ISBN: 9781557883995