The old HD may start up, changing out all drivers
which presents quite a show springing up from the System Tray which you need to monitor closely to do the requested restarts
If not you can clean install 64 bit using the licensed version ISO provided in tutorial, plug in the second HD after install to access it's data or install the Paragon app to adjust the second HD since the newest version doesn't seem to have a boot disk but adjusts a target Windows 7 from inside another OS. Then reboot and try to trigger the old HD to boot.
If you end up only using the old HD for data or storage you can move the data to another partiiton to correctly delete the old OS partition in Disk Mgmt