Angle milled Intake

I am going thru a bunch of Slant parts I aquired long ago to start my first Slant build. My intentions are to build a foot brake bracket car that I can also use to go get ice cream in. I have a clifford intake that has been angle milled in both directions.
Front to rear 2.5 degrees I understand this so during hard acceleration the carb is level.
What I don't understand is that it's also been angle milled left and right 2.9 degrees with the left side being the low side. Can anyone tell me the reason behind this ? So what should I do with this leave it or mill it flat ?

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