so i stumbled into a local autoparts store curious what i could do for my stripped out bolt hole,instead of the standard "spring" type heli coil the guy had this awesome kit for doing spark plugs.its more of a threaded sleeve.it comes with a tap thats specially designed to fit "original" threads and it  automatically bores and cuts in new threads for the insert.best news is the insert fits original drain plug.it may be a couple weeks before i get this kit and do it but ill be sure to post pics!

Thats the kit I,ve had in mine for years.Works great and no issues.