rockm

I would give the plant at least three years' untouched growth after this trunk chop. Drastically trunk chopped Japanese maples can die back severly, even two or three years after the chop. Reducing the roots soon after this operation could add to the problem.

Don't worry about branching at this point. You want the tree to recover and working on a leader. Don't get ahead of yourself. Branching can be developed down the road.

Don't count your chickens before they're hatched. Wait til the tree recovers to do anything further.