... At any rate the pieces I bought fit in the space just fine and line up perfectly with the top lock receivers. ....
I am not sure which one of the padded trim pieces give you trouble, the larger ones in the center, or the ones on the corners?
Also what do you want to drill? The trim pieces to fit the hole in the windshield frame or drill new holes in the frame to fit the holes in the pads?
Also, are you sure you got the correct pads for a 280SL and not the ones for a 230SL?