That's a complicated fix for for a simple problem, but that's what keeps welders in business, I guess. I'd just use a pipe tap to chase the threads and install good socket-head pipe plugs with PTFE (Teflon) pipe dope. That's probably too logical for people who like to do things the hard way.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!