You would have to either locate an “as built” 1/400 Balao sail, or scratch build one. The postwar conversions were to Guppy type streamlined step sails. As such, the masts were enclosed in the upper part of the step sail, with the lower part surrounding the bridge station. I do have an article somewhere in my files on scratch building a Balao conning tower/sail that the sub was originally built with. The article built one for the 1/180 Lionfish kit. Might be a bit of a challenge at 1/400. Deck guns would be another additional item.