Been a busy beaver today - gotten all the cultists built and even converted a few of them.
My two favorites:
the "commissar" squad leader with a swap from his sword to a warhammer (and a more dynamic grip, IMHO) and his shotgun for a lasgun - when I glued it in place, I found it looked quite like a tommy gun, so I glued the lasgun's grip to the foregrip, and I'm really happy with the result.
The other is the heavy stubber/flamer model with a head swap and a genestealer cultist shotgun. I kept the original head tilt, as it fits the model and makes it look kind of odd, which is oddly appropriate. I greenstuffed in the hole in his front and back (for pegs for his weapon and backpack, make his apron into pantless overalls.
The model I stole the head from for the shotgunner above, otherwise unchanged except for the head swap. The other is the 'big axe" cultist leader swapped to have a chainsword and an autopistol instead.
Two more simple swaps. I'm happy with the one with the dynamite sticks (the one of the left - he used to be a melee model), but the right one didn't quite turn out, as to get the gun to fit I had to build the right shoulder of the model out in an odd way - this time, a not a "good odd" like the head tilt guy above.
For 40K, I intend to run all the shotgun guys as autoguns, but this way I can use them as a necromunda gang with more weapon options... though, I didn't check to see if shotguns are legal under the Necromunda chaos cultist rules.