They might want a real sub, so that when the next flood hits the Big Easy, at least that artifact will survive! I heard that much of their collection was damaged by the hurricane. Looking at the architectural "fantasy" illustrations, it looks like they are hoping to have a Type VII U-boat (or part of?) and a V-2!! Maybe their illustrator was smoking some dope when they put the presentation together.
There are companies (with Hollywood experience) who will build you this kind of stuff, but it is EXPENSIVE and ultimately, the purists like us will not be impressed by a "prop" when we can see the real thing somewhere else. Sorta of like why I never visited EPCOT and probably never will... let me get intestinal distress by visiting the REAL third World, not a Disney repro!
PF