Quick update on my original post:
- I created a "Kindle for Calibre" folder and used "Automatic Adding" to get Calibre to import (then delete) from this folder.
- I organised the original Kindle folder in days and opted to copy/paste one day's batch of Kindle books at a time into the newly created "Kindle for Calibre" folder and let Calibre import them.
- Some days had only 20 or 30 books to import, some days had over 100, but this kept things methodical.
- I've had to re-import some Kindle books (in batches, as they cannot be identified) as the DRM were not always erased. A Calibre reboot rectified this.
As an aside, I read about
Belvedere to add books into Calibre and this works very well indeed.
All new Kindle purchases are now automatically copied into the "Kindle for Calibre" folder and imported into Calibre without any action on my part. This takes care of any future Kindle book purchase.
I still have to run "Find Duplicates", then "Edit metada in bulk" and "Quality Check" to tidy things up...
Thanks for all the comments. It's useful to find out how people would/did deal with a similar situation.