lol someone has already mentioned it but yeah, misrepresenting CR there a bit gabe.
As for Codex Edition - I would suggest shrines are buildable in T1, where in your troops can get a mark of the appropriate god as an appropriate upgrade. Then, in T2 your troops with a mark can become chosen marines, like Rubric, Berserkers, etc.lol
Then in T3, you get all the demons, with T3 Call ins being greater demons.
I think this will work showing nicely the expansion of chaos forces as they mount up their presence - plus also leaves plenty of space for chaos preds, dreads, havoks, raptors, cultists, chosen, possessed, etc.