I see you have watched the same how to video using bondo. Slightly more work for a much better product IMO. I’ve done two this year and don’t see myself going back to borax/pinning.
In the same boat. I have had a new lefty stainless t3x .243 in my safe for a few years with plans to re-barrel to 7-08, but might just have to look into loading for the .243. I have a 20” encore rig in .223, but want a left bolt setup.