The Battleship Iowa will be operating with her original US Navy callsign of NEPM on 11 May 2017 from 0900PDST to 1700PDST, 1600UTC to 2359UTC.
The ARRL announcement is located here, and the official MARS announcement is located here.
Frequencies used to transmit from the ship, and the frequencies we will be listening on, are shown below.
The transmit frequencies have been assigned by Army MARS for exclusive use by NEPM, so you shouldn't have any trouble hearing use as nobody else will be transmitting on these frequencies.
The "Grey Radio Gang" WILL be operating the ship's "legacy" on the 75/80 Meter and/or the 40 Meter frequencies.