Any help appreciated - - on barefoot ski image optimization

Any help appreciated.
Working with Photoshop 7.0 trying to color correct and optimize an image of my son barefooting to prepare for giant vinyl print to create a stand up cut-out on a foam board.
I will attach 2 downsized images for comparison.
As you can see one image has nice smile but no sunlight and other image has great sunlight but no smile.
I need to optimize for CMYK printing the smiling image. I know a bit about levels, but don't know what to change for midtones, highlights, etc. to try and correct this smiling image as best possible.
Unfortunately I did not set up the Canon EOS Xsi camera to save RAW images at 17 megs and the boat owner is not wanting to go out again for another photo session. Original image is 4.5 megs jpg which I crop image, adjust histogram by "sliding in the sides", convert to CMYK, sharpen unmask at 98%, increase brightness with middle slider in histogram, expand size up to 72 inches tall by 54 inches wide and also set to 150 pixels per inch (may try 300), save as LZW TIFF.
After that image is like 400 megs, then import into illustrator CS and tile out just the face of a 72 inch X 54 inch and it's amazing pretty clear for 100:1 file size increase (13 X 9 inch sheet).
I have access to CS4 on Mac only  - - don't know if CS4 Mac file will have any big advantages over my 7.0 in Windows . . .

Hmmmm, wonder if anybody ever created a plug in for photoshop that allowed you to add more lighting to an image, as in light coming from behind the photographer - - like sunlight effects ?