Gozen Iwa or Gozeniwa?

This seems to be variously spelt Gozen Iwa or Gozeniwa depending on the source. TdG tvhc_tvhc what's your preference?

I’d do it all in one word as it’s a place name comprising a noun plus an honorific, which are usually romanised as one word I think. Though most websites I could find have it as two words.