I knew I wanted a unit of Vargheists, as they offer some much needed mobility to the largely ponderous and slow moving undead army. While I love the battlefield options provided by the Vargheists, I didn't care for the GW models at all. I find the bat-like faces to be silly and not at all in keeping with the overall bestial aesthetic.
At this point all that was left to do was to green stuff in the hair to fill in the gap around the heads, add the wings, and throw on some paint on the models. For me, the final result better reflected the bestial nature of the art work and made for a natural tie in with the other more animal-like GW undead models such as the Varghulf and, of course, Dire Wolves.