After renaming all Goblin .blp's, .anim's and .m2's to Human and changing the models of the latter to 831 & 832 (the Goblin male and female models) in CreatureDisplayInfo.dbc, it turns out everything works fine except their heads, which as seen in the pictures below, are either black or are using the texture of another race.
How do textures in World of Warcraft become black and how could I fix this particular error?
PS: My patch:
patch-4.mpq
EDIT: I have also tried swapping Forest and Ice Trolls with some other default races and they all work just fine. Upon further research, I've noticed their texture files seem to include both "FaceLower" and "FaceUpper", which the Goblins do not have. And that simply implies the Trolls do have faces whereas the Goblins do not, hence why they appear this way in-game. To resolve the issue now, I would require the Goblin faces, but there are absolutely none to begin with. Everything to do with the Goblins can only ever be found in Common.MPQ and Common2.MPQ, yet none of that comes with their faces.
Where could I obtain them from?