I deleted the .dbc files you mentioned and put it in the Data/Cache folder but it didn't work ingame. :/ Not sure what I've done wrong.
I have no idea what you have in your Data folder, but try to put the MPQ into your Data folder and rename it to wow-update-base-13624.MPQ
Given you have file extensions showing, otherwise adding a .MPQ won't do nothing besides give it a double extension(one false and one real but hidden) which would make wow ignore it.
using the number 13624 in the example because 13623 is 4.0.6a's highest patch number. so naturally it'd be best to shoot for a tick higher than your highest patch, if you have other patches, then make the number one tick higher than your highest patch.
is there any way to get the WoD models working for players only without the buggy NPC stuff?
You'd have to use the CreatureDisplayInfo.dbc and CreatureModelData.dbc file that came with the patch if you wanted that to work. but to do so, you'd have to fix the CreatureModelData.dbc because 4.3.4's version of that file has an extra column per row entry, so you would have to format it to 4.0.6a's specifications to avoid a crash or a freeze error.
As to how to do that, it's not a simple matter(not saying it's hard or difficult, just not very straight forward) so maybe someone else will come in here and explain it for you if anyone decides to help out.
But basically what's in those files are new entries that point to the LK character model data files and then switching out every npc DisplayID's( a few thousand i think ) that used the character models to the new custom id's in the CreatureModelData.dbc that point to the classic character models so the textures don't get screwed up. This way players would have WoD characters and NPC's would have Classic characters.