Sorry I did not back to this earlier. I had typed a long reply several days ago, but it got lost in Cyberspace, I guess.
I used the old winshield as a template. Some of the stock windshileds have a gap around them, so leave yourslef a 1/4" extra or so if yours does. I used a fine blade on a handheld reciprocating saw with good results. Don't go too fast, or you'll soften the Lexan & clog the blade, but it's not too easy to cause this problem.
I left in the OEM gasket after cutting out the glass, and laid the Lexan on there. I used a 1/4" by 1" aluminum strip for the center breace I drilled & tapped it for a 6mm screw, then used button-head screws to attach the winshield to the brace. My wipers hop over the button-heads easily. I used threaded aluminum collars to pull in the sides of the windshield - like rivets, only threaded for removal.
HTH