The up side to front lighting a GBC.
vary limited skills are needed.
if all goes well it will take less then a few hours to do,
you get to say "hey, look what I did" and get a pat on the back by God, invisible door's will open up, and you'll suddenly have the confidence to be able to do anything.
and if you don't play GBC games, then you have a really nice paper wight.
you risk having to kill the GBC screen, and having to get another, and another, and another.
The up side to using the GBA SP in a DMG case,
you leave the entire screen / frontlight intact,
you will acquire some useful moding skills, like
button relocation, adding the L & R buttons,
with a little case work, you should be able to get good placement on the cart slot.
but relocating the cart slot would let you use it anywhere you want and give it more of the original look.
and your using the whole SP, that lets you play a lot more games.
might take you a wile, day's even, heck if its your first mod and you want it to look good, week's.
you get to say "hey, look what I did" and if it looks great, people might nod there heads and smile,
I'm not trying to talk anyone into or out of anything. I just don't see the point in having every remaining GBC destroyed over the next few years for starter projects that people don't use.
save the Frontlitghing GBC for people who want them.