Well after looking for a few i didnt really find any cabinet smokers that were true reverse flow smokers. I did find some that said reverse flow, what i noticed is the fire was still directly below and allowed heat and smoke to still rise straight up to the food, the only thing i noticed was the exhaust line was lower in the smoker and not at the top.
Not sure if i was missing something if there is another cabinet smoker out there i was missing with a diagram please post. But if these are the kind you were refering to think they could be mimicked as in my cheesy 30 sec diagram below. Heat and smoke rise to the top and fill barrel before exiting through the exahaust below the food level but high enough not to choke out your fire. Hey i could also be nuts but this seems the most viable to get what i think your after.
Weber performer, Smokey joe, Weber go anywhere. Mini-wsm, WSM-Soon