trying to figure out (short of creating a new repo from current code) how to mirror the heroku git repo for this on github
Can't you add another remote for it? One for GitHub and one for Heroku, then just push to both when you want to update.
yeah, that's what I ended up doing. :) first time using git. These old bones have been ground up bad by CVS/Subversion :P Here's the announcement: https://news.ycombinator.com/item?id=5535827