I have several large arborvitae on my property that form a privacy hedge (~30 feet tall, 10 feet wide) but they weren't planted close enough. Any recommendations on a variety that would work? Emerald arborvitae isn't tall or wide enough, leyland cypress is too tall and wide, and I planted a green giant arborvitae that I fear may get too tall.

Is there an evergreen that will grow relatively quick and top out around 25-30 feet and no more than 8-10 feet wide? Dark American (nigra) arborvitae maybe?