I was given a fairly open project a little while ago- just take a daemon prince kit and make sure he ends up nurgle aligned.
With the daemon prince kit, I've found that a head swap goes a very long way, so I chose a head from my bits box- it comes from a Crypt Horror. It isn't exactly the same size as the normal prince head, but I think that actually helps it out- it makes it seem less like the original mini (since the head doesn't look more deformed than the core mini.
After having him there, my client let me know that he preferred a winged Daemon Prince (ok, the mobility adds a lot of utility on daemon princes).
If I had realized this from the start, I'd probably have used the normal daemon prince wings, but I really loved how the back spikeds looked with the fleshy-nurgle scheme. So I opted to use another set of wings from my bits box- from the same kit as the head, even: