Just a thought, if there is enough meat around the hole ,, look at threadserts instead of heli colis.. They are installed like a helicoil but designed for aluminum, they use them on the head studs of heavy power VW cases. I found them once through an aircraft supplier. They have a special tap with them and the threads engage DEEP they are Iconal If I recall so really tough but match AL expansion ..
Guns are like parachutes
If you need one and don't have it
You will never need one again