All model 230, 250 & 280 SL’s came as all plastic or plastic with a rubber-like black lever. Your ‘69 would have been equipped like the latter example.
I have seen after market solid metal (in either in black or chromed) lever replacements. This would only work on the latter example as well, since the earlier unit was a solid piece.
I’ve never seen these installed. Please post a picture of how they look.