yea alumiloy is stronger than the base metal in the first place, and yes it can be re tapped

 

If you have a freind that has a welder have him set a bigger nut over top of the broken bolt. Weld the bolt to the nut from the center of the nut. If it is a good weld you can then turn the bolt out with the welded on nut. This has worked many times for me and my freinds. It all depends on how good you can weld.