One issue is to realize there are two "refill" amounts. One is for a complete overhaul and one is for a "filter change". The "filter change" amount is what you want.
The job can be made a bit "cleaner" by using an electric extractor pump to pull the fluid out of the pan FIRST. Then you aren't spilling/sloshing a lot around as the front of the pan is lowered.
THEN, the "filter change" refill amount can be increased a slight bit if the converter happened to drain-back, to increase the amount of atf in the oil pan. So, might need an extra quart or so.
On a COLD transmission, aim for the "ADD" line rather than "FULL", as the fluid will expand when heated. Of course, this is with the engine running at base idle speed. After getting to this point, anything above the "ADD" line is good. Recheck after driving at least 10 miles to get the fluid up to normal temp and in all places. At this point, mid-level is better than completely "FULL".
Have fun and make sure the car is firmly on safe jack stands!
CBODY67