bzr to git syncing

Does anyone have experience syncing a Bzr repository to git? I would ideally want two-way syncing, but even the bzr->git route would be a start.

We're starting with a Git repo that was converted from CVS and it being kept up to date. The CVS repo will be converted to Bzr sooner or later, and at that point we'd need to sync from that one. We would need to keep the revision IDs coherent, i.e. not re-convert.

I have looked at the git-bzr scripts that go the fast-im/export route; this fails unfortunately (bzr side I think). Also, I'm not sure if that would preserve revids.

It strikes me that patches / merge bundles would be cleaner way to do this.

(If you care: The background of this is that Emacs is switching to Bzr, but my downstream project, Aquamacs, and a bunch of Emacs devs want to use git themselves, so I'm trying to find someone who can do this.)

Thanks in advance for your suggestions.