From TowerHobbies (the best RC site in the world!) it appears that the airplane starter shaft is keyed.
I was browsing through the link you gave us and it appears that there are different adapters.
Here is what was leading me to think it was keyed:
http://www2.towerhobbies.com/cgi-bin...?&I=LXJC36&P=V
So you could probably make something other than the propeller cone adapter!
I would not use epoxy. I do not know the melting point of epoxy, but chances are it may melt.
I would make a metal sleve insert if possible.
I am not exactly sure what you are trying to do with the under cut shaft so I can't really help you much.