I don't like that virtual either.
The oak tree style suits the tree very well, but the problem is that those heavy branches have no taper, and are also too straight for this style. So, I would start shortening them, util they are approximately half of their current length. But you need to do this during spring, to make sure that good back-budding takes place, and you don't end up killing the branches.
So, during the next season I would shorten the thick branches, and let the new growth elongate unchecked, making sure that I remove most of the unwanted shoots. At this point, I would not do any carving, because the new shoots may dry out and die if you mess with it too much. Then next year I would wire the new leaders in place, and carve down the big stubs, working towards creating tapered branches. As it was said here before, boxwood is slow to heal, so successful carving is the key.