I feel for you. I traded a 326 in a couple of years ago and they are a pain to change the belts on. One more reason I dislike Kubota mowers.
Unless I totally missed it I had to pull the deck out and that is a pain. Seems like you have to unbolt something on the gearbox......
If you see a video on the 327 I would think it wold be the same. I know I have a ZG 222 and it is pretty close to the same thing to change that belt on.