Sounds like it was built like a tank to resist U-boats, and fitted with diesels sized for aircraft carriers. The Wikipedia page is worth a read. To fireproof it and save weight the Navy specified building the ballroom piano out of aluminum. Eventually they found a naturally fire resistant wood for the instrument.
The propellers are on display in museums already, and the interior was gutted and fixtures sold off long ago. Why the hull mods? Maybe the heavy compartmentalization required by the Navy still obstructs putting in big rooms???