Here you go! I just finished restoring the windshield of my 29 tudor (which also should have had an electric wiper). Like yours mine had a vacuum wiper installed along with extra holes. I closed up the extra holes leaving only those that should have been there. (picture 1) Notice the rectangle that I masked off to retain the bare metal around the right mounting screw so that I will have a good ground connection. A little dielectric grease and the rubber mounting boot will keep it from rusting.
BTW1: I also replaced the intake manifold with one that has no vacuum port (picture 2)
BTW2: If you do return you model A to its correct electric wiper - feel good. Not only will your wiper not stop when you go up hills, but you will among few who make the effort. At the recent Cider Mill show, of all the closed cars that should have had electric wipers (including my friend's newly restored 29 tudor), only one actually had an electric wiper!