This ISO works for both OEM (Core) and Retail (Pro) x64 clean installs:

File Name: en_windows_8.1_with_update_x64_dvd_4065090.iso
Languages: English
SHA1: 4652DC6EBFEBE02C6A63E167C36E3FAEDFB93999

Generic keys (and procedures) are the same as before.

I know for sure because I have done both successfully.