The windshields are the same, but be sure to get a seal for an early 2800CS. I think all the 2000Cs came with clear glass.
I seriously doubt anything else will fit.
There are aftermarket windshields available for E9s, but they may not fit well. I have one and while it fits ok, if you look at it from the side, it is noticeably flatter than a BMW windshield.