well i took a spark plug tap with the same size threads as the original hole and ran it in with some grease on it and pulled out a few metal shavings then took a new plug and it thread right in all the way tight far as i can tell.

Didnt ever add a helicoil or insert, The plug looks to be sitting flush and will tighten down all the way with a socket like the rest. Weird maybe i got lucky.