I did a very dumb thing................. I couldn't find the correct socket to use to remove and put on a thermostat, so I use an air gun and I over toruqe the bolts and stripe the internal hole.

What is the smartest solution for this problem....

There is a product called "heli-coil" it is a kit with a drill bit, tap, insert tool, and inserts. There are purchased according to the threads you are trying to replace (8x1.25, 10x1.5 etc.) The only problem is you need enough room to drill out the old threads.

Aluminum block so be careful. Has to be speciality product.