I've done the Lexan windshield on a street/strip car exactly once.... came to the conclusion the weight loss is not worth the aggravation to me, just for approximately 15-17 lbs lost. It scratches of you try to wipe dust off it, seems like it even scratches if you breathe on it. Can't run wipers AT ALL. Rain-X is the best you can do
Tighten a screw too much and it cracks, shows waviness where every screw is, just sucks if you ask me. A short life if it sees much sun too, it glares and streaks something awful
Do all the other windows if you want, but if this is a car that is going to see any street time, my advice is that it is a waste of time and money to do the windshield.
Find some place else to spend the money making 5-8 more HP to make it up instead.
Better yet, spend that Lexan money on a vacuum pump for the engine and make 40+ more HP.