Naib
you are close to solve the mess. the missing step is to manually unmerge the 3 hard blocking packages.
this is how I do the perl upgrade.

Got 73 packages to install, then ICode: Select all
emerge -va1D dev-lang/perl $(qlist -CI dev-perl/) $(qlist -CI virtual/perl)
Code: Select all
emerge --ask --verbose-conflicts xfce-base/xfwm4 xfce-base/xfce4-panel