I've been toying lately with colorizing Ninja Gaiden Shadow for Game Boy Color.
Right now, I've got every colorization subroutine ready, so I only need someone skilled in NES-esque palettes and pixelart.
The game uses 3 color background tiles, which could be improved a lot by editing the tileset and adding an additional color. Also, it will probably need some tweaks in the tileset, in order to adapt it to the 4 colors.
The graphic artist shouldn't need to do anything special other than editing the pictures I'd send to him/her, adding color to them and editing the tileset if needed. That's it.
I wish I could release it for the game's 30th anniversary, but since I'm quite bad at graphics, I'm going to need help (I don't think I will release it otherwise).
PD: Yes. Mega Man World 5 DX is still coming. It's on a short hiatus as it overwhelmed me.