I would consider using a cast iron plug to fill the hole. Its done a lot in machining to fill holes in blocks and heads. The iron plug will move at the same rate as the block when it heats and cools, a steel plug will not. Do as Hotrod lincoln said, drill it out to bigger size pipe thread hole so that the new hole is inside the old one. Use a solid iron plug and really get it tight. Cut it flush, sand or file it smooth, and all will be right with the world! Joe
