First, take care with those old pipes. Make sure you’re using two wrenches when you’re loosening the union connections. Assume the position, and then turn one wrench while holding back with the other. Don’t take any shortcuts here because if you attack old pipes with a single wrench the torque you create can, and probably will, break the pipe.
A hand truck with a few strategically placed blocks of wood will help you move the old beast out of the way. And if you’re planning to take that old radiator down a flight of stairs proceed cautiously, and with plenty of help because an antique radiator can weigh hundreds of pounds.