What do you think the stress limit of a biblically accurate saraph (winged serpents that burned things) would be in eat god?

It really depends on what role you want it to play in the hypothetical playset in which it appears. Non-disaster "minibosses" generally cap out around SL15, while SL25 is a good benchmark for disaster-level "bosses" that appear without other NPCs backing them up, so if you're picturing it as some sort of boss encounter, that's a good place to aim for. On the other hand, if it's just, like, a Guy…