Might try a helicoil with the green loc-tite on the outside.
Tapping for a larger fitting was a good idea too. Otherwise they sell this stuff called "Lab Metal". It hardens up like metal and has the appearance of dull aluminum. It is workable and can be tapped for use for repair. Just can't have it over 350 degrees.

http://www.neverseezproducts.com/labmetal.htm