Neon spark plug thread repair help

I like that 3/4 depth cutting and leaving the bottom as is. Would get fresh meat for the plugs and keep the valve seat area untouched. I had an old Mazda that had a perpetually loose plug on the #3, seems the head was cross threaded at one time and the threads were just gone. I took a 90 boot and made a metal bracket off the exhaust bolt and bent the thing so it would press a piece of wood against the 90. It kept the plug in! That engine was so ghetto: I ran a piece of all strut over the thermostat housing using threaded rod off 2 bolt bosses as those stat housing bolt holes were stripped too. I never had an issue with either farm repair. Distributor seized up on me and snapped the shaft. That was all she wrote.