The thing is what is called decklage. That is the relitive angle of the wing tail and engine all together. The incidence is mesured from an emagenary line(water line or horizonal datom). To acheve extra stability training plane is usualy engine a few degrees down the wing leval and the stablizer slightly doun. Then the airplane is balanced nose heavy. To me an airplane looks better if it flys so the nose is slightly nose down in leval flihgt. In the real airplane they wanted the pilot to see over the nose so they wanted it to fly with the fuslage slightly nose doun. If you see a real Piper J3 Cub in flight it flys nose down a supre Cub flys more leval. The J3 you solo from the rear seat so you want the nose and the front seat passenger down out of the way. In the Super Cub you fly from the front seat so it flys more fusalage level.