the recipe is just a base that you can expand in any direction that piques your curiosity- generally adding components from creatures will cause your homunculi to exhibit traits from those creatures.
i think for the naga i'd add ~5 parts naga scales to the recipe.
and for the vampire, about the same amount of vampire fangs.
please collect your fangs and scales ethically.
...and if you're feeling adventurous, why not try a mix of both? there is no discovery without a little adventure

