Run compare scripts to check if there's anything you've installed locally that's not set to install in other machines.
This article has some good tips for downgrading versions https://dae.me/blog/2516/downgrade-any-homebrew-package-easily/
To setup private github tap credentials, see https://gist.github.com/mlafeldt/8e7d50ee0b1de44e256d