Thermocouples and platinum resistance thermometers are the obvious choices for high temperature.
You might be able to find a IR thermometer sensor too on a breakout. Standard photodiodes can't see
far IR at all and are no use for temperature until red/orange heat kinds of temperatures!
You could make a differential radiation meter by using two DS18B20's or LM30's, one in view of the
stove pipe and one shielded from it, but that's also sensitive to local air flow/ventilation, not just
radiant heat. Black epoxy packaged thermsensors are surprizingly sensitive to radiant heat sources
and pick up body heat quite noticably, for instance.