"I tried magnifying the 'blackness' looking for brush strokes and any tell-tale signs of the original outline..."
Not once it's been through Photoshop you won't.
Here's a photo of the one-off mock-up:
Designed by David R. Davis as a long range fighter, and appeared in 'Flight' in 1942. It's obvious why he called it the Manta.
Good shooting
skytrain - the floor is all yours.