Alternative Beast builds

So, was wanting to build a couple of Beastmaster units
. Not too bothered about using the proper models. My army doesn't contain any Wyches or other coven units so my beasts will represent the menagerie of my Haemonculus which he keeps for experiments etc. I was thinking about using:
1 Box Chaos Spawn
1 Box Chaos Warhounds
1 Box Hellions
1 or 2 Boxes Warmaster undead carrion

The Idea is to build Beastmasters out of Hellions using bits of warriors/Wracks, only issue is making the "beast control" masks, any ideas?
I plan on making the Spawn into a couple of Clawed Fiends, using the spare bits to "weird up" the Warhouns a bit, anyone familiar with either of these 2 kits? is this viable?
The Undead Carrion are obviously are Razorwing flocks, does anyone have experience of these models? I was hoping to get 2 bases from each box. is this viable?

I hope someone can help me. I plan on having 2 units, 3 'masters each one of each choices per unit. Is this a decent idea? I love the concept of the variety of these units to complement my coven lists with the general theme of warped craziness.

I've made some beastmasters from Hellions. One has a Scourge mask (tho painted to look like bone, unlike my Scourges which have metal masks), and for the other I took a Kroot skull from one of the trophy poles, cut off the Hellion's head above the facemask and glued the Kroot head there. I tried the same with the Clawed Fiend skull from the Venom kit but it's shape is not as well suite for it.

Yeah, i was thinking the same about scourge masks, was maybe gonna use top half of scourge mask, bottom of normal bare head and go from there. I have a fair few scourge masks, although I am looking to build 6 Beastmasters overall, so can't be wasting too many, lucky I've got 3 boxes worth of scourges really! The other thing which did occur to me is that the finecast Beastmaster models and the illustration in the codex both give him the appearance of being heavily muscled, do the Hellions from the box not come out a bit, well, scrawny? Also, would be grateful to know what you did with the arms? Are they easy to convert? They just look a little to me as if they are designed to hold those Hellglaives and nothing else. I have quite a few of the whips, from warriors and wracks so that's not going to be a problem at least, as long as I can get them on easily enough.

Moving this to Painting & Modeling section, with other similar threads. Gob.