1976 Dart Overheating and other issues

I think your plan is valid.

Do #1
Do #2 but use the proper temp.
Do #3 with correct pressure.
Do #4 with hoses off you can see if the impellers on the water pump are intact and turning.
Dont do #5 at this time if engine is running well otherwise.
Do #6 refer to factory service manual

Additionally I would:
do a pressure test on the cooling system.

look for signs of combustion gasses in the coolant.