Mounted on the stove pipe before the barometric damper, my thermometer reads about 1/2 of the stove temperature. On a seasonable winter day, my stove will be cooking along at about 300* to 350* and the stove pipe thermometer will generally read about 150*.
Mount your stove thermometer where the body is single wall, but well above the fire box. I have mine about 6" below the top and about midway between front and back. Traditionally with wood stoves we mounted the thermometer right on the top. I know some guys do here too. My stove as a false top to channel forced air, so I have to go to the side.
The Saey is cast iron isn't it? If so 600* should be on the safe side as a max. If plate steel, opinions vary, but the general concensis seems to be about 550* should be about max.