Hi Paul;
I am so glad that my posting in the other thread was able to help you out in this issue! 
Yes, it is the 64bit version - just not named correctly yet. You will see that if you upgrade to any of the newer 9.x releases that the EXE in the BIN folder is named "gswin64". The 8.71 version though is installed into the "Program Files" folder as expected for a 64bot version and would be caught by the O/S if it were loaded from there as a 32bit. 
A "bit" (no pun intended) confusing. 
Regards ...Chris