Moving banksia rose
 

In my butterfly garden I've got a Banksia rose that is getting out of
proportion (canes 10 foot). I want to move it to a place where it can grow
huge, and put something smaller in its place, likely a Bonica rose.

Is it too early to do this? As an alternative, someone had suggested
cutting the roots a foot out from the trunk with a spade and leaving in
place for a month before moving the rootball.

Opinions? Ridicule? Off-topic rants?