Air-fuel ratio schooling needed.

I would try to go as lean as possible with idle, to prevent fouling the plugs.
Lean mixture doesn't hurt anything inside when the engine isn't 'working'.

The 14.7 number is just a "chemical" ratio that means all the air-molecules have burned completely with all the fuel-molecules.
The WOT-number you can only find out (controlled) on a dyno, or on a dragstrip.
The Cruise number, you can try to lean it out for economy until the engine starts to very lightly surge while driving.

Combined with a vacuum gauge and proper ignition curve you can get very good results in tuning the engine.