I just saw your post from Ray Richardson. The National Grandee Hotel was actually at the southwest intersection of Min Tzu East Road and Lin Sen North Road, across the street from the “back gate” of the HSA East Compound, the gate that pointed straight into the signal compound. The gate was located sort of behind the theater and library. I returned to Taipei in 1984 and took the attached photos. By that time the East Compound had become headquarters for the Chinese Military Police and their main building was directly inside that same gate. The first photo is looking north along Lin Sen Road; that’s the CMP hqs in the center and the white building on the left corner is the hotel. The second shot shows the same two buildings from a little closer perspective. The third shot is the hotel itself from the diagonally opposite corner.Google Maps, it's right there. Search for "Riviera Hotel, Taipei, Taiwan" and go to Street View, which will put you at that intersection and you can look around from there.
Thanks again to Ray and Les for all this good info.