You need rhinos and 8 man squads the excess points can go to other things. 8 men zerker squads are very effective even though they are not 16 strong they will have it easy driving around and killing heavy weapon teams and infantry squads while your obliterators/defilers/vindicators pick off the enemy's close combat units. Kharn is an okay choice of HQ as he is basically a daemon prince thanks to gore child and he can also hide in rhinos and zerker squads. I would add some vindicators with demonic possession into the mix as it is khorny and pie-ny/ish.
Sir Nom Nom will eat your brains if you dare not to click on him. Where do you think he got his name?