Yes! It's possible to use windscreen from '88-07 pre-gen on '86-87 1st-gen. Here's an '87 I rescued in boxes.
Put it all back together
Ended up using headlight, windscreen and mirrors from pre-gen.
Bolt upper holes together and you'll see lower holes don't quite line up. I marked from back side where to drill new hole in windscreen to fit. Thinking back, I should've marked from front and drilled new hole in fairing. Then final result would've been cleaner without unused original hole in windscreen visible.