WOW!! I actually had a not too different experience not long ago. I had a good look down the Alum rabbit hole but was never game to try it.
I ended up getting a thread repair dude, that specialises in bolt extraction, to work it out. That basically amounted to a diamond tip bur followed by a heli-coil!
Still, a lot better of a job than I was doing with cobalt drill bits and blind fury!!

VERY keen to see how you go...