>I found the left 0.2 deg. greater than the right.
>Does any one know what is acceptable?

Yes this is about the largest difference that will allow good stall characteristics and flight efficiency.
	 If you measure at 2 different locations on each wing and the error is less that .2 degrees average it should be good.  I like measuring at the trailing edge of the tip inboard of the wingtip and the flap side of the flap aileron junction.  This produces a good composite look at your wing average angle of incident. 
	Greatly improved accuracy can be achieved by using a digital level.

Jack Webb
L 360, L IV
ATP, CFI Airplanes & Instruments, Multi, & Sea
Many Type Ratings
Experienced Experimental Test Pilot both multi and single engine
Former Chief Engineering Test Pilot for a Major Manufacturer
AeroSpace Engineer BSAE
Ohio