Just for info. When breaking in a rebuilt engine you don't want to be working on carburetor(s) and other parts at the same time. Running the engine has priority. You may be busy fixing water/fuel/oil leaks and troubleshooting. It helps to have a known good carburetor for break-in. It's one less thing to worry about. Once you are satisfied with the engine, you can install the duals.
There is nothing really wrong with a torque tube except most have worn bushings and seals. Then like anything else, before you rebuild, you need to inspect the ring and pinion gears as well as the $$ bearings. I would drive it as it is for now.
