Before removing the old door handle, take a picture of how the door latch bolt on the inside of the stove is orientated to the cast iron door crank on the outside of the door. The steel shaft should be pointing up when the cast iron crank is pointing down.
If you have a roll pin holding the cast iron crank to the shaft and you can not remove the roll pin, you will have to remove your old door handle by cutting the latch bolt on the inside of the door with a hacksaw.