Where to run the valve cover vent tube?

As the engine runs with a PCV system, the air is pulled from the breather/oil cap into the engine by the PCV valve.The PCV is mounted in the opposite valve cover thru the crank case and into the intake either thru a port on the throttle body/carb base or direct port of the manifold.
So your idea is correct to pull from the base plate of the air cleaner pulling filtered air into the breather cap.