Honestly, the Gentoo-style global blacklist (package.mask) to force a downgrade is probably a better approach for cases like this. Epochs only make sense if your upstream is insane and does not follow a consistent numbering system.
Gentoo also considers the repository (+overlays) to be the entire set of possible versions so simply removing the bad version will cause a downgrade, unlike debian and RPM systems where installing packages outside a repository is supported.
