Iowa class would be kinda overkill. No planes or pt boats should be able to get close to an Iowa class BB because of it's armament. The North Carolina class were built in the Late 30's and would be quite adequate.
Um the armament of BB.55 was almost the same as the Iowa, minor differences.
Hull Number:  BB 55 
Keel Laid: October 27, 1937 
Launched:  June 13, 1940 
Commissioned: April 9, 1941 
Decommissioned:  June 27, 1947 
Length: 728 feet 5/8 inches long 
Extreme Beam: 108 feet 3 7/8 inches wide 
Mean Draught:  31 feet 7 inches normal, 35 feet 6 inches maximum 
Displacement: 36,600 tons standard, 44,800 tons full load 
Complement:  2,339 (144 officers and 2,195 enlisted) 
Speed:   28 knots 
Armament:  9 16-inch/45 caliber guns
20 5-inch/38 caliber guns
60 40mm/56 caliber guns
48 20mm/70 caliber guns