It has a Windows Experience Index of 3.8. It did perk up considerably after putting in an SSD 3 or 4 years ago.
In the end, after a harrowing day, I had success.
1. Removed the 240GB SSD from my wife's PC
2. Cloned it to a 960GB SSD using Macrium Reflect
3. Moved the rescue partition to the end of the drive using Minitool Partition Wizard which then allowed the boot volume to be expanded to over 600GB.
4. Installed the 960GB SSD into the computer then, because it wouldn't boot at all at this point
5. Ran Windows startup recovery.
The PC now booted, completed the Windows Updates, and then upgraded without incident to Windows 10. So: 8 hours to restart the computer, 1 hour to install Windows 10.
For comparison: When High Sierra got jacked on my then-new 2017 MBP, I was able to start up from the internet and reinstall it. Now THAT's style!