Depends on the engine type.
Go to
http://www.356a.com
punch in your engine serial number (located on the base of the generator stand- something like P*602782) in the database
if Normal then tin gloss black
if Super then tin gloss black, fan shroud silver
if Super90 then tin gloss black, fan shroud white
If you want true authenticity then get Brett Johnson's books on this at
http://www.amazon.com/exec/obidos/tg/detail/-/0929758102/104-6078584-6582328?v=glance
If you are feeling cheap then go to the 356 members car gallery and browse engine pictures at
http://www.356registry.org/Members/index.html