Try finding photos of the bombEr from the bombardment group your dad was with. The circle and the letter W goes on the tail. The space break in the circle, the larger set of number goes between it. The artwork goes on the nose - usually on the pilot side.
The UNITED STATES AIR FORCE decals go on both sides of fuselage.
The decal with the 15 and wings also go on the tail rudder on both side.
As I said, try finding pics / photos of the aircraft.