Finally, her "nun dress" arrived from China after delays. Although Sadako doesn't technically wear a nun dress (she simply wears a normal long white dress), the generic ebay nun dress looks very identical and actually looks pretty good.
The nun dress is a little tight, but it managed to at least fully cover Sadako, who is using an S17 body. If this nun dress is already tight for that kind of slim body type, I guess it won't fit the normal, thicker TBLeague bodies.
All in all, I'm very happy with my first attempt to recreate a beloved character of mine Maybe next time I'll create a well for her to climb out of haha!