The GBC frontlight kits aren't that great. It looks terrible unless you adhere the screen to the lightbox layer (or whatever it's called) using LOCA, like on a cellphone. Backlight looks much better than frontlights as a rule, anyways so I'd personally go with that.
I'd swap the analog and dpad/buttons layout. It looks too low and uncomfortable how it is now, and with a raspi2 most of the games you will be able to play well you'd probably use those more over the analog.
Also I'm not sure what's to the sides of the screen but if those are speakers it would...
2017 bump mainly because I keep forgetting to ask @ttsgeb about xboxen internal power supplies; if he has an extra one and how2 know which version I need
Unplug the backlight and shine a flashlight or something at it to see if you can see any sort of picture at all. I had an aftermarket ps2 screen (intec I believe) where the backlight washed out anything else on the screen. Hopefully the same thing here and you can fix it by LED modding it.
Not sure if there are any existing models but it would probably be quickest to 3D print one. Also if you need replacement clicky tacts they are just old mouse buttons.
Best dpad and/or joystick ever IMO