Hey 'cat, sorry for the tardy reply. Thanks to help from another user with the same setup I just got the kWorld USB stick running on the ODroid - and that's a C1+, you're right that I failed to mention that.
I did manage to pull one build on arm from apt-get but since then it appears they are all gone. I looked in release and stable but it seems everything is intel or amd. C'est la vie.
I'm building now - I had no idea it was so big! My last build failed but that was 4.0.8 so I've git cloned release and, well, fingers crossed.