The owner's manual I have shows you have the valve bolted in the correct position for gasoline.
The way modern gasoline has alcohol in it and freezes the outside of a manifold (surely the inside also).
It probably would not have made a performance difference even if that valve was the wrong way.
All it does is divert the exhaust gases to flow around the intake manifold to help vaporize heavier fuels.
And, if you want a new manifold, I believe production in the U.K. is in the pipeline. I know my manifold is past condemnation