The Yamato would probably easily sink two Iowa's in a gun battle The Iowa's were not built to counter the Yamato's. The last class to be laid out, the Montanas, were. They had four triple 16 inch turrets, were longer, faster and more heavily armored. They would have displace 71,000 tons which was just slightly less than the Yamato. The Iowa's weighed in at 45,000 tons
The Japaneseknew their stuff in naval gunnery. Probably the best in the war. They kicked our asses many times. There was a third ship in the class, the Shinano which was competed as an aircraft carrier. She was sunk by a submarine while moving to another base. She was not completed, watertight doors were missing, pumps were working but crew not trained in their operation. 4 torpedoes did her in. She did not have all the armor the battleships did weighing in at a mere 69,000 tons. They stopped adding it when the conversion began.