Our keystoker 90K running full throttle, the flames would touch the top of the stove. As long you are not pushing hot coals off the end of the grates, you should be fine. I have been running it for 3 years without any problems. I have had the sides get upwards of 400-500 degrees (with magnetic Thermometer).
Your convection blower takes the air across the top of the stove, so it will always be washing the metal of heat into the room.
Not sure if adjusting the combustion blower (covering the inlet) would help decrease the flame height? Never tried it. That will affect your draft a bit and make sure your fire doesn't go out either.