Gapps are already included in the stock ROM. You don't need to flash inverted gapps over it.
If you want inverted gapps, find a black theme that themes everything with skins.
If you want to take the route of custom roms, try Slim Kat as it has a The Real Dark Slim feature which makes everything inverted. See first feature, http://www.slimroms.net/index.php/slim-bean-features
This really belongs in the Q&A forum.