It's easy to change the angle.
Look at the mounting points under the dash. The legs of the windshield passes through the body and are bolted to the cowling bar.
I would loosen the bolts, should be two each side, and see how far they spread apart.
I have found the mounted welded in incorrectly. And who ever mounted the windshield would make it work. Thus warping the windshield frame. Installed under stress.
You can use washers to adjust the gap.
By drilling new holes you can change the angle. If the cowling bar mounting points are two narrow you can add a larger plate, maybe 2" x 4" x 1/8" (or 3/16") to give you the second hole you need.
I'll try to post a picture to better explain it.
https://www.gt40s.com/threads/pictur...t95628&slide=0