I just used the USB Thumb drive created by the MCT process, wiped the HDD of Linux, chose to install the Pro version which had been done couple years ago. I told it I didn't not have a key and it finished the install with a Local Account. After up and running I checked the Activation and it was activated with a Digital License. Obviously Microsoft Servers saved everything and was relatively painless. The only issue was the video card worked fine in Linux but in Win10 the resolution was low and proper drivers couldn't be found, apparently too old so I changed the card and all is good.