I think you've got two trees there. There's a clump style with a little upright shohin sitting on top of it.
If you continue with the current direction I think the mismatch between the top and bottom will increase. There's no link between the upper section and the tangled mass of roots and shoots at the bottom.
I might try layering off the top (just above the point where the trunk splits into three major roots). Then cut back the lower shoots hard, and wire more movement into the next set of twigs that emerge. You've got a good basis for a twisted, tangled clump style there.
The advice 'air layer it' is over-used, but in this case I think it's appropriate. If the layer doesn't work you still have an interesting clump to work with.