If you need a new seal for around the door, the closed cell foam is the way to go if you are not up for making the "universal fit" door seal material work for your door shape.
If you need the actual insulation in the door (between the door liner and the outer shell) then make a trip to a local insulation supply company. They can help you select a dense, easy to work with replacement material. This is a good idea if the unit has sat outdoors and been exposed to the elements for any time.
Most range restoration will replace the insulation around the oven and door liner as a matter of course. After so many years of cooking grease, humidity, etc., the insulation absorbs contaminates and becomes less effective. The Maytag Dutch Oven range claimed to have forty pounds of rock-wool around their ovens.
