You desire this to heat the branding irons for the goats?
I wouldn't know....maybe, but I'd bet in order to keep the flu gasses going up the chimney, you'll not get the temps that you're aiming for. What I mean is if you damper the exhaust enough to keep that much heat in the "oven", then you'll have CO leaking all over, and if you allow the exhaust to go up the chimney, the high temps will go with it. Just guessing!