Donald, it's grand!
I can't tell from the pics which of the longer branches are (or would best be) the main leader. It does look like you could lean the root ball one way or the other to keep one of the 3, *if* height reduction isn't part of what needs to happen for it to fit inside, and you aren't after more of a globe shape.
When you do cut something off, don't just at the edge of the main foliage mass. If you do, the new growth will already be out-of-bounds. I usually prune stems off at or very near where they branch from the main stem.
