Usually this is cause by the arm on the wiper motor being 180" out of rotation. usually wiper motors have a shaft with 2 flats on each side, unbolt the arm and rotate on the linkage ( while moving the wiper arms ) then reattach.

Some wiper motors have an adjustment for parking but I have no idea if this is what you have or not. ( and even at that it is a small range unless the wiper motor was assembled upside down / 180 out ,)

Pitch this to the vintage section of this form as well.