No, there is no model... which means you can do whatever you want for it. If you dont really think thats allowed I recommend a very quick cure- google image search for 'hellpit abomination'... the conversions it pulls up are all stunning and have one thing in common: absolutely no common features whatsoever... basically imagine something between a satanic demon and a nurgle spawn and you probably have a winner

Just make sure its on a 50*50mm monster base and you're sorted (although you could get away with a giant base.. think they are 50*80mm).