The easiest way to balance the GP Super Stearman at home is to clamp two pieces of wood, about 16 inches apart, to over-hang a table about a foot. Tape a long dowel (old push-rod) to the underside of the top wing, located per the instruction manual. This is your fulcrum, i.e. CG. Now place the model's fuselage between the over-hung sticks with the dowel resting on the sticks. Set the stab to zero by adding frontal weight, using a level on the stab. Done! (Update: The cabane interferes with one long dowel...use two dowels.)

Wing incidence.
Forget what you heard, forget what the so-called "expert" wrote in the modeler's magazine lately, forget what you see on the Tower website. Her's the straight scoop, proven with three Stearmans:
With the stab set at zero, the bottom wing should also be at zero degrees. The engine should be set at minus one degree. The top wing should be set at Minus two degrees.
Result: 1. the model will not climb when advancing the the throttle to full.
2. inverted flight will require less down elevator.
3. there will be less tuck to the wheels when flying in knife edge.
4. bounced landings will be a thing of the past.
Setting the upper wing requires two longer L-brackets at the rear wing struts. Do some trig to to find the new hole location in the bracket. Along with this, the cabane location will change at the fuselage, and the aft screws may miss the hardwood mounting block. I simply drilled new holes in the cabane.

Good Luck!