I remember seeing this tree, also called 'Morioka Weeping', at UBC several years ago. I have read differing descriptions of growth habit of this tree, but I remember the one at the arboretum as Quite tall and very spectacular. Consensus seems to be that this Katsura will ultimately top out at 30 - 40 feet in height and width. Does this sound about right?
What happened was it was pointed out a weeping Magnificent katsura in circulation in western gardens was actually a weeping regular Katsura with an ability to grow tall, unlike most (all?) others. It was then renamed 'Morioka Weeping', based on its introduction history. I've seen an old photo showing a towering specimen in Asia, if the same clone that 30'-40' will be exceeded.