Reuters: BP Plc successfully replaced a failed blowout preventer from atop its ruptured Gulf of Mexico oil well late on Friday, the top U.S. official overseeing the spill response said. Retired Coast Guard Admiral Thad Allen called the equipment switch “an important milestone” toward permanently killing the leak that spewed more than 4 million barrels of oil into the Gulf from April 20 through mid-July. “During the period of time between the removal of the damaged BOP and installation …