Italian-built battleships for Germany

What changes if Italy builds battleships for Germany in exchange for German shells?

Germany might receive Atlantic-adapted Littorio-type ships and earlier 15-inch guns, but Italian capacity would first need major expansion.

German shells and Italian hull construction could exchange useful technologies, including earlier German access to 15-inch guns. Yet Italy's yards were already stretched by their own Littorio program. Without new infrastructure, exports would reduce rather than increase total Axis capital-ship production.