You might want to double check that request.
1) You're trying to migrate from a full blown SCADA package to an embedded HMI. Cheaper, but serious downgrade in capability.
2) You're switching from one obsolete software package to another. It probably isn't a huge surprise that WinCC v6 is now at WinCC v7.5, but WinCC Flex 2008 is just as old. The current equivalent software is WinCC Comfort (or maybe advanced) v15.