Woah... sombody actualy made one. http://wargamesterrainworkshop.co.uk.previewdns.com/?product=coatl-south-american-dragon also worth checking out... http://wargamesterrainworkshop.co.uk.previewdns.com/?page_id=11
I know it's long out of print, but the Shadow Run Feathered Serpent is still the gold standard for Coatl models.