Why not tell us the outcome you’re looking for here.
Your old instance is currently 1.6 - but your title suggests you want to run a rebuild, which will also upgrade it - is that correct? If so then yes, restoring to a fresh new install will be less painful.
If you’re just looking to start the 1.6 instance instead of upgrade then the advice will be different. Without the hostname change thrown in you would usually just copy the contents of /var/discourse between servers. As long as the destination machine has docker installed it can just be fired up using ./launcher start