Upgrading CiviCRM that is set up outside of the Drupal docroot with symlinks
This looks overall good!  A few suggestions though:


I would advise moving Civi 4.3.8 into the sites/all/modules folder separately from the upgrade.  Since this is a fairly unique setup, it would be good to eliminate it so that if something goes wrong, you know this isn't the issue.  You should be able to do that just by enabling maintenance mode, removing the symlink, and moving the CiviCRM folder to where the symlink was.  Make sure there are no references to the incorrect location in civicrm.settings.php or in Administer menu » System Settings » Directories or Administer menu » System Settings » Resource URLs.
I'm not sure what settings_location.php is, that's probably specific to your setup
Depending on how abused your database is, you may encounter upgrade errors going from 4.3 to 4.7.  If so, don't forget when rolling back to drop your CiviCRM database and create a new blank database before restoring!  A restore will not delete newly-created tables, and CiviCRM upgrades choke when they try to create a table that already exists.