I don't know if this changed from 230SL to 280SL, but my 230SL Parts List shows the following hardware needed for the whole hood strap assembly. It does't say which stuff is for which end of the strap.
007981 004226 - Lens head screw, sheet metal (2)
000127 005203 - Lock washer (2)
007985 006134 - Lens head screw (2)
000125 006407 - Washer (1)
000127 006203 - Lock washer (2)
I would assume these are all available through MB dealer or many other parts suppliers. Any SL specialist part supplier would be able to get you the right screws and washers by describing what you need.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420