Make Karak eight peaks 10 slot city or at least provide free garisson in the main settlement building for Dwarfs, Skaven and Greenskins like other major/capitol citys gives you.
For example if you capture it with Clan Angrud you will have to build pasture (because of the much needed growth), the unique dwarf building (because of all the good stuff it provided), the unique Clan Angrud building (same here).
That will leave you with only 4 slots for income, garrison, public order, untainted, recruitment and growth buildings.
That is horribel. This city is supposed to be the biggest city in the World edge mounts, only rivaled by Karak-a-karak and dwarf citys is massive in size.