Help me come up with a theme for my GSC army. I don't like

I've got a couple ideas, I really don't like the way whatever the guardsmen looking units look.

For chaos gods I'm either gonna choose nurgle, tzeentch, or khorne.
For nurgle, I'd use their new zombies and maybe give them more mutations than they have.
For tzeentch I'd make some of the goat guardsmen guys out of their tzaangors, and use the gladiator dudes bitz to give the mining suit guys bare chests with mutations.
For khorne, I'd like to do the blood pact and maybe still some naked chest bodies or sculpt some mutation on sigmar models.

Alright so I've decided tzeentch renegades, how can I make them look neato as GSC.