Have you considered starting a similar project on your server? Since the Fenris is about as big as you can get (vertically) in MC, how about starting to build an Aten or Argo?
You've never seen the Herc i made on Pece's server have you? Cause we kinda beat you to the punch on that one.
It can be seen easily from dynamap if you don't want to log on, alongside all the other awesome stuff.
The idea of an Aten was thought of before, being fewer then 64 meters tall and relatively flat it would be able to fit 1:1 without mining down at all. unfortunately, I know that the Herc took me so long, even mapped out -similar to your fenris plans, only on graph paper- that the idea of doing an Aten alone scares me a bit, even with the use of CreativeStick. (which is kinda cheating, at least by the Fenris project standards)
Perhaps when the Fenris is done an Aten project can begin on Pece's server