OK, so first I adjusted levels (moved the shadow mark toward the start of the left side histogram) and then slided the mid tones back toward the left side, so I will brighten up the midtones). In this way, I spreaded the histogram across the whole dynamic range (loosing and clipping colors and tones, and exposing quite a lot of noise but thats the price you pay for a not too good scan of a print).
I did some sharpening with Unsharp mask.
hope you like it!
Chen