If you used this particular tank in a built-up model with a side mounted front intake engine, you would need to mount the entire tank outboard of the center line of the airplane, just as if it were a profile. If the tank were centered within the fuselage, it would be too far inboard and its relationship to the carburetor would be incorrect. If the engine was upright or inverted, or rear intake, you could achieve proper fuel system geometry with the tank closer to the center of the airplane. It's all about the ability to get the vent tube 1/4" to 3/8" outboard of the spray bar.
I hope that's not too confusing.
BB