Typically you use a large amount of grease on the tap to catch the shavings. You turn it in a little, pull it out, clean the shavings, re-apply grease and repeat till its done.

Still I'm not sure how you can do it with spark plug recessed as deep as it is in the head.

https://www.amazon.com/Time-Sert-M14x1-25-thread-repair-4412E-111/dp/B00YPUN39G/

This is the best type of thread repair. Helicoils can work but they don't like repeated insert and removal. They can unthread.

https://www.amazon.com/CalVan-Tools-38900-Valve-Triton/dp/B000Z9D6KW/