Surprisingly, the yoke of the Gorebeast Chariot lines up with the Beast of Nurgle pretty well. I just have to use a little green stuff to link up the yoke and the beast a little more convincingly.
Yet, as well as this came out, my plans have changed. Originally this was to be the mount for my Chaos Lord but the Charioteers proved a little too hard to customise. Turns out Putrid Blightking parts do not marry up well with this kit and that's where practically all of my “Nurgley” parts come from. So, rather than have an uninteresting Lord model I'll just count this as a normal Gorebeast Chariot with the Mark of Nurgle.
That said, Matt and I have been discussing using it as an actual “Beast of Nurgle Chariot” whilst paying about the same points as the Gorebeast Chariot. The way we reckon it, at least right now, is by dropping the Daemon and Regeneration saves but keeping the Slime Trail and ability to call challenges will make up for the lack of Killing Blow.