Sorry, it won't work. If you take away the wall and the shadow, the hair will just look inexplicably squashed flat on that side.
Anyway, it would be impossible to take away the shadow, I'm afraid.
Good! Now keep tweaking the gradient so that the colours match the existing colours down the right-hand side of the subjects as closely as possible. The better match you get down there, the easier your masking task will be.
Ok, great. Well, this'll be nice and easy.
Since you said your scanner is ancient, go ahead and photograph them. Let me know when you've done so, and we'll discuss the print steps.