Aluminum heads and spark plugs

I belive Ford tried this and then had issues with the plugs breaking off when trying to remove them Due to debris on the threads.

Also they would blow the plug right out of the head from lack of threads. They make a special kit for the fords to repair the head in the truck. I would be leary of doing that to your heads.

But once you mill the threads away it is only a little welding to fix them. Your heads, Do what you believe is money well spent. But as for me I would have left them as they were.