WK and MCR barrels come with widened gas ports compared to those of a standard AR barrel. I don't know if the expanded gas port is truly necessary, or just something the original WK designers did to allow the firearm to eat every ammo, at the possible expense of beating the rifle parts senseless. The TNA adjustable gas block should help tune down gas, but whether a standard AR barrel's gas port provides enough gas for the system to properly actuate, I do not know.
Alberta Tactical Rifle Supply (ATRS) makes .223 barrels with widened gas ports for the WK and MCR on demand. You can contact them to confirm if they can make a 7.62 x 39 mm barrel with a rifle length gas port.
International Barrels Inc (IBI) made 7.62x39 mm barrels with mid length gas ports in the past for the now extinct RWA 180B and the RWA WK180C upper, and for sale separately by RWA. If you contact them directly, they should be able to do the same with a rifle length gas port.
Finally, you could call, not just write, actually call TNA directly and ask if they could procure the barrel from their supplier. They recently began selling pencil barrels for the 180c and MCR platforms in .223, and said supplier could likely produce them in 7.62x39 mm in rifle length gas port if asked. Hell, that's something TNA should be carrying to go along with their 7.62 x 39 mm bolt.
