A possibility is to buy a threadless stem adapter and a threadless stem with some rise and a removable faceplate. The adapters have moderately long quills and you have a wide choice of threadless stem types and almost all have removable two or four bolt faceplates.

I see no reason why you couldn't cut your Nitto down by making a cut parallel with the current bottom. However, the bolt may then be too long to tighten the wedge and you wouuld either have to find a suitable length bolt or extend the threads on your stock bolt.