I like the concept. My thoughts are, you could go two ways with this though one is more stockworthy, and the other more artsy (but will still be accepted by some of the agencies - some would eat this up, others would say too much processing in Photoshop). If you go with a light background like you have, try smoothing the wrinkles a bit with the dodge tool. I would also encourage a lot less makeup on the model.
On the other hand, a darker background with creative use of the burn tool around the wrinkles, and darker lighting, would give a terrific artsy effect that seems to be trendy in some circles for advertising these days. My favorite individual that does this is Andrzej Dragan:
Andrzej Dragan PHOTOGRAPHY
Here's a tutorial on how he does it (don't worry if you don't understand, you can follow along pretty easily)
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There's also a young kid (OK - 16 or 17 years old is a young kid to me) that does this in Canada with homeless people. His name (and web site) escape me at the moment but it is the same concept.
Have Fun!