Apt Upgrade AND Downgrade all packages to Current Release

I recently upgraded from Ubuntu 12.04 to 14.04. While using 12.04, I installed several packages via PPA's. Now that I've upgraded to 14.04, I've discovered that some of the PPA packages from 12.04 are still installed. All of those PPA repositories were removed during upgrade.

I would like to uninstall the PPA package versions of any package that exists in the Ubuntu repositories. For example, I have a SVN version of Audacity that is newer than the version in the Ubuntu repositories, but I want to replace it with the Ubuntu repository version.

I want to do the same thing with all PPA installed packages. I tried pinning this in /etc/apt/preferences.d/main

Package: *
Pin: release a=trusty
Pin-Priority: 2001

Package: *
Pin: release a=trusty-updates
Pin-Priority: 2002

Package: *
Pin: release a=trusty-security
Pin-Priority: 2003

Then

apt-get update; apt-get upgrade

Unfortunately, it didn't downgrade any packages like I hoped. For example, running apt-cache show catfish shows version 1.0.2-2 is available from the Ubuntu repositories, but I still have 1.0.82-1~precise~ppa1 installed.

I want to Downgrade all packages to their current release in the Ubuntu repositories.

I believe that you want to use ppa-purge

sudo ppa-purge ppa:name-of-ppa/to-be-purged

man ppa-purge indicates that this will "automatically down‐grading all packages in a given PPA back to the ubuntu versions."