I think this worked… I used ProjectToCPlane to project the point and the line and then drew a line between them with Perp Osnap. That line looks pretty perpendicular to me in the top view.
I then created a line by picking the int point (selected/yellow in image) as my base and used elevator mode to create the point on the original lower line, which is what I wanted. Thank you so much @pascal !
Image: (Right) the bottom curve was the original and the top is the projection.
