Yeah, that was exactly my thinking, and by making it a bolt-on unit the plan is that it could migrate to a bigger drum at some point. Here is what I came up with:
The top is just some 1/2" angle iron with little slits to make it bend, which I drilled and tapped some holes in. I nipped out the bottom of my old reactor to serve as the hopper. Also, i welded on a curved flange to the massive Leitinger nozzle. I drilled an 11/32" (8.7mm) hole, and will test that to see how it fairs. The hole is reamed out on the inlet side, and its super easy to poke a welding rod in there to break up slag. I am just blown away by how easy MIG welding is even with such a massive piece of steel.
Here is the Mark II model with everything RTVed and bolted together. I think I am going to fire up my charcoal retort soon here, and my plan is to make half a drum of hot coals, then dump on 15 gallons or so of engine grade charcoal that I suspect is too wet. Ill let that bake for a while, then seal it up.