In your case you can probably tune the engine fine with the high tank, but when you roll inverted (or push to negative 'G' to be more accurate) you now have a low tank. The engine will now be much leaner. The uniflow tank won't change that at all unfortunately.
Actually it can help, but only within limits. Obviously if the needle is below the bottom of the tank or above the top of the tank it will not help. If the center line is at say a 1/4 tank above or below the needle it will not help when the tank is full or 1/4 empty but will help when the fuel level is between that.