Depending on what your friend was wanting to use the helmet for there is a company here in NZ that has pioneered the use of hard shell leather helmets.The warbird guys love them apparently. They provide real protection but still look the part in a warbird.
The company is called Campbell Aero Classic NZ Ltd
www.campbellaeroclassics.com
Although manly WWII they may have what your friend is after if he is looking to actually use it in anger so to speak.
regards
Kev