Cleon
Legend
Other ones I mused on converting were/are the Ice Maiden and Gazer (from WD14), Melodemon (WD20), Shim-Shari (WD29),
It doesn't make much difference to me, so which one would you like to start with?
Don't remember much about the Ice Maiden or Shim-Shari, would have to look them up.
The Gazer was a one-trick pony, plus the original statistics and description are so bare-bones we don't have much to work with. Although I guess that'd help make it a quick conversion!
I've long thought the Melodemon was a cool monster, so if you want a tiebreaker I'd pick that one over the beholderkin.