Ed
I've used hundreds of these inserts for thread repair in aluminum parts at work. They allow a much larger thread to be used and might get you back into more "virgin" materail. Im not sure how much welding was done but it doesnt look like they had to move them very far? I know a lot of heads use helicoils but if you have the room you could possibly use these.
I guess I forgotten you didnt have orings in the heads. Any thoughts about changing that?
Have you pulled the pan or cut the oil filter open?
http://www.mcmaster.com/#standard-th...nserts/=i9gqnt