I hereby declare this conversion done!
Standard Troopers:
Command Group:
Regarding the musician’s curious face, @Uther.the.unhinged: The poor guy actually used to play the trumpet. However, he had to switch to drums after losing half of his teeth because the unit champion behaved awkwardly with that maul of his in some battle. That is the reason both for the single tusk and the expression of perpetual hatred. 
Dwarven Bucklers to cover the transition between dwarf and bull torso are an idea I stole from @Iceman, so thanks for that 
I freely admit that I went cheap on the shields: instead of scultping the devices myself, I just cut up some GW skulls and only added flames to create the flaming skull icon, as I’ve already done a number of times. But I think that the hats and faces are doing most of the optical heavy lifting in this conversion, so that should be fine.
The task of getting these things painted seems a bit daunting to me right now, but I will get around to it some day. 
Edit: In retrospect, I’m glad that I did only seven of them, because they do not rank up well at all. It will be just about possible to arrange these on a KoW cavalry regiment base, I think.