Aeon418
Almost right. But I think you've confused the initial letter Nun for a Gimel. It's easily done. They are very similar letters.Fascinating.
Hiss and Whisper = ShChGh (if I did this part right) = 358
The word for "Hiss and Whisper" is the same as that for Serpent - NChSh.
Also I flip my transliterations around to make them read from left to right just as if they were English words. A rough pronunciation would sound something like "Nachash".