Making your own smoker
Ive built one that was about the same size and I used a 4 inch square tube to connect the fire box and the chamber. I actually built it for a buddy and he loves it. I use Rustoleum high heat paint its rated for 1200 degrees. I mainly use an indirect smoker but have been building UDS smokers for a couple of months now and they are alot simpler and maintain their temperature more closely than the offsets Ive used. I would suggest you build a mini UDS and if its not what you want you should still be able to convert it to an offset.