I don't think the incoming air cares which way the engine is turning
I reversed a stock G23 by turning the coil over and replacing the rotor on the crank...there is no need for the key, it's only there to position the rotor when the engine is assembled..I quit using keys on my conversions about 16 years ago..The keys on a tapered crank are too soft to drive the rotor if it comes loose anyway...O a straight shaft it's another story, but not many engines are like that..I know of at least one