Dang that is a fine looking skin, Mus! Your wind-streaked dirt/oil/grime really add to the detail, and the metal texture and shading looks right on.
The only other thing I can suggest is to check the placement of the "Dallas Doll" noseart on the right side of the fuselage. According to Guppy's detailed profile, the last part of the name should end up right under the last exhaust stack - yours looks too far back on the fuselage. I'd be tempted to duplicate that layer to give it a bit more definition, too, but that's entirely subjective.
This one should find its way into the game pretty quickly!