Surprised no one said anything about an EDM approach. When set up right, it will burn that tap out with no further damage to the hole in just a couple minutes. Then plug it like Jerry said and retap it. An EDM is one of those tools that are not cheap and used very little. But when you need one, they work really slick.

Don

1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!