Shizuhiko Haraguchi served as a gunnery officer on the Musashi, one of the largest battleships in history, when it was being fitted in Japan before it departed for the Pacific in 1943.
He said he recognised underwater photos taken by Allen's team of a large gun turret and a catapult system used to launch planes.
"I recognised that main turret, which I was assigned to," Haraguchi, 93, said in a telephone interview from his home in Nagasaki, in southern Japan, where the ship was built, fitted and tested. "I felt very nostalgic when I saw that."
Haraguchi left the ship just before its departure because he was transferred to an aviation unit in eastern Japan.
The apparent discovery on Sunday of the Musashi comes as the world marks the 70th anniversary of the war's end.
The Musashi sank in October 1944 during the Battle of Leyte Gulf. About half of its 2,400 crew died, and only a few hundred eventually returned home alive.