This is a kitbash I did recently with a box of cadians and some void junkers. I ordered the junker sprues from Scotia Grendel http://www.scotiagrendel.com/Products/index.php?main_page=product_info&cPath=59_64&products_id=432
The heads I used were from Pig Iron productions http://www.pig-iron-productions.com/hd2-kolony-militia-head-sprues-p-13.html
The plastic void junkers work perfectly with guard plastics. The backpacks line up really well. The arms have ball joints which makes them very easy to cut for any pose you may want. The shotguns look pretty good and scale well with heroic scale models. The riot shields are fantastic, I see a lot of potential for anyone wanting to make some adeptus arbites conversions.
I plan on running these as standard vets or grenadier vets, the shield conferring a 4+ save ala carapace armor. I'm considering kitbashing the leftover bits with some warhammer cavalry to make roughriders. The junker bodies are a little stiff but they'd work well on horses. I also think there's potential to use them to make some inquisition stuff. They'd be a good starting point for making your own assassin models.