I started out with a Brunco 190 furnace and tried burning that beast with wood, bituminous lump coal, anthracite in stove and nut size. My neighbor bought a Brunco 120 at the same time and is still using it, but only burns wood in it. He could not get his to burn coal either. From my experience with the Brunco 190 and observing my neighbor's Brunco 120, the only good thing I can say is they are probably the best constructed and welded furnace out there. The design though, was definitely for burning wood. It doesn't burn coal well at all. Bituminous is possible, but hungry, anthracite without control and will not keep burning, because the design has serious drafting issues for burning coal.
If you are going to keep that beast, I would definitely drill the ash door for a spinner or two. This will change the whole burn characteristic and actually allow you to burn coal in it. Back then, I wished someone would have confirmed that idea when I still had the stove. The guys at Brunco kept telling me it would void the warranty, it wasn't tested that way, we don't know if it will work, it was my chimney, my coal, the way I was firing it. So, I got so frustrated with Brunco, I sold the furnace and bought a Clayton 1600. If it wasn't for the guys at Brunco, I would have never found a more superior and efficient operating furnace. They deserve the credit for making me shop the competitors.
Back to the Brunco, I found when I attempted to burn coal, flyash would build up very fast in the V-shaped secondary baffle plate, almost closing off the flue outlet. Keep an eye on this area. I didn't and let the ash build up. Then kept the ash door open in order to keep the fire burning. Eventually over firing the unit and warping the steel baffle plate. I wanted to run a domestic hot water coil in it and found the back of the stove had two 1/4" plates spaced about an inch or so, making it impossible for me to drill through it, that close to the flue outlet.
Other than drill the holes for a ash door spinner, I would consider insulating the red heat jacket. Boy will you notice an increase in the heat transfer efficiency into the duct work.
So, once you correct the deficiencies in their design, you'll have a pretty good reliable, almost indestructible, high heat producing monster of a furnace. Keep us posted on you decision and progress. Hope this helps,