I've only been able to find references to the restaurant being along Nathan Road and not the exact address, so if anyone can confirm or deny it would be helpful.
Wednesday, July 19, 2017
Golgo 13: Assignment Kowloon - Sonny Chiba (1977) - Nathan Road, Mongkok
Another establishing shot that shows a road junction with the prominent restaurant sign in the background for the San Ah (i.e. New Asia) Restaurant or 新亞大酒樓. As far as I can tell this restaurant was almost directly opposite the Mayflower Restaurant which Thomas was able to help locate when I was looking at locations for You Only Live Twice. This means the junction we are looking at is most likely to be the one where Shantung Street meets Nathan Road on the east side of Nathan.