genrege, the table you have shown only shows the cruise performance. It doesn't say anything about the engine power output during a climb.
Here is a possible scenario: During the climb you fly with a low-ish airspeed, say 90 knots. You have full throttle, the engine is developing about 90-100% power but due to the low-ish airspeed the prop is limited to 2700 RPM.
You now convert your climb to a cruise. The speed rises, you close the throttle gradually to keep the RPM below 2700. Once you reached your cruise, the throttle now limits the prop to 2700 RPM and engine power is 70%. Airspeed will be 124, according to the table. (Sea level power according to the POH picture you supplied.)
So you can lean this engine when it is cruising at 2700 RPM (at sea level) since engine power is 70%, but you cannot lean this engine when you are climbing at 2700 RPM, since the engine is producing more than 75% power.
Remember that prop RPM is dependent on a lot of factors, and one of them is airspeed itself. In one situation (cruise climb) 2700 RPM might equate to 90-100% engine power, while in another situation (Vne dive, for instance) 2700 RPM might equate to maybe 20% engine power.
Last edited by BackPacker; 14th Sep 2012 at 09:30.