Ask HN: Open sourcing a previously closed project

I'm working on cleaning up the codebase for one of my side projects, and there are things in the repo history that I don't want floating about in the wild. Is there a list of security best practices for this sort of thing? I'm thinking of starting a new repo with only code from the latest "safe" HEAD. I'd also love to hear about people's personal experiences doing this, not limited to the security ramifications.