If you were appraising this house, would you make the assumption that the highest and best use is the current use? Of course, you would need to know location, zoning, condition, surrounding buildings, etc.... but....
This renowned piece of Portland architecture was torn down to make way for additional church parking in the 1950s.
The chances that I would have determined the highest and best use for this lot (regardless of where it was located) would be a parking lot would be slim to none.
There were several masterpieces similar to this one in the Portland area which were either torn down to make way for apartment buildings, mid rises or made into multi-unit dwellings in the 40s through the 80s.