Hi Kbonsai,
I have done a few of these kinds of trunk chops in the past. You will most likely get more shoots emerging around and under the cut site, I'm kind of surprised it has pushed these new shoots already but then again, you are in Perth!
I'd be leaving the growth to get a little bigger/stronger and then choose a new leader/branch combo to go with, keep the branching that gives you changes in direction and the movement you are looking to develop by performing the chop. I wouldn't be too concerned about inverse taper with such small shoots, you have a bit of time to let them develop before removing.
I did something similar as part of the shohin comp a few years back ... see the link below if you want to check out how I went about it
viewtopic.php?f=158&t=22396&start=0
The tree is still going strong and the trunk chop is healing over nicely, I need to update it's progress - maybe when I repot in a few weeks. You can do a lot to Chinese Elms - tough little nuts!
Good luck with yours.
