Have you seen the militia/cults list in HH book 5?
Because I'd use that. It's like the Inquisition list but moreso, with a vibrant and deeply eclectic selection of units and armaments, designed to be as generic as possible and therefore allow a huge range of 'human' army types. You can use it to build an army made of everything from feral world cavemen to actual Thunder Warriors to cyber-enhanced tech-guard to lunatic cultists.
And there's not anything game-breaking in it either. About the 'worst' thing is that your only Dedicated Transport cost is the Gorgon Superheavy Transport, but that's not as great as it sounds, because 1.) the thing's massively expensive in points, 2.) the things MASSIVELY expensive in real-world cash and 3.) it might be nearly indestructible, but two twin-linked stubbers and two mortars is not exactly a terrifyingly level of firepower.
I really like the list; I've been building a 30K-era pre-Necromunda army with it.