Well not a GTR, however today as I am still in Japan for a while longer, I visited a dealer near to Tokyo and looked over a 1974 Z1 (local market variant, 750 cc instead of 900 as exported to other countries though otherwise identical).
It was very clean, showing just over 10,000 kilometres from new and priced at around £12,000 sterling equivalent. The all important exhaust system was standard and as new.
The dealer was quite organised and offers a full touring support service for Japan, something that I have not seen before. If you suffer a breakdown or similar, they will collect and repatriate the bike to their workshop for repair, leaving a loan machine in its place for you to continue your trip with, all for a fixed fee.
Initially I considered exporting it to the UK for use there, as I intended to send one of my oldies from the UK to use on visits here. The import of a motorcycle for use in Japan seems to be something of an unknown, however (unlike cars) so I think that I might buy it and leave it here to use.
Either way I've wanted another Z1 for a long while now, so it might be the one for me!