That photo you took of the big old building, was the old Native saw mill that was still working in 1978. Tarawera was the end of my block when I was a rabbiter and based at Rangitaiki. It was a favourite haunt of mine. That old hut that you were at was an old tallie shack for counting the native logs that were taken out of the area at the time and well before 1978.
Wow. That's awesome. Wandering around was a bit like a discovery tour. The main house on the way in is being left to the elements as is the shearing shed There is some serious history out there When you go up a track you just come upon old native logs cut and then left there years ago