Alternator bolt threads stripped in the head

Low cost, easy way, is as already mentioned, swap heads side to side; next you could take a cutting torch, lay the flame directly on the bolt/easy out, and blow the metal out of the hole, it won't stick to the cast iron, nor will the torch won't cut the cast. I personally have not tried this but I have heard of it being done. Next option is to remove the head and take it to a machine shop that has EDM capability, this one will cost, not a huge amount, maybe $30.00-$50.00.

Good luck.