I found one on Ebay.
Its pretty inexpensive and has accurate English subtitles. I own a copy of this myself, and I must say I'm very pleased with it.
http://cgi.ebay.com/KING-KONG-vs-GODZILLA-Japan-BEST-VERSION-W-S-Stereo-DVD-/220617886379?cmd=ViewItem&pt=US_DVD_HD_DVD_Blu_ray&hash=item335dd9caab

The Catch of the Day!