Which is the proper phrase to follow a negative declaration? For example:
I will never go, even if [not doing so/doing so] means death.
Which of the two would be the correct to use?
This is tricky to parse, but only the former makes sense for what you appear to be trying to say. "Even if not going [not doing so] means death, I will not go, ever" is the sense of it.
I strongly recommend you rephrase, though, since when I first read it I misunderstood what you were saying and almost wrote the answer wrong! Suggestion:
I will never go, even if it costs my death.
Or perhaps (using an idiom):
I will go only over my own dead body.