The short answer: yes and no.
Yes built one years ago. Revised it three times, and didn't reverse flow.
Building using one flue between the barrels will not produce enough airflow and maintain temps high enough. Have tried using one flue barely able to reach 200 degrees. Learned that the hard way. Had to tear down and install a second flue. Added a difusser plate inside the upper barrel to even the temps. The smoker only lasted one season.
Here's the history of that drawn out tale.
Custom Klose Backyard Chef... of Snot, and a 22.5 WSM
Lang 84 Deluxe kitchen, Lang 60 Mobile - The Damsel II, Lang 48 Patio - The Damsel, Bubba Keg Grill - RIP, Double Barrel Smoker and a BSKD