Hi Derek,
I also noted the difference in angle between the metal pan and frame (a badly designed match). However, as my seat pans and frames are original, have the same dissimilar angles as pictured by PeterB, and have the pan sitting within the frame, I must consider that there is another issue at play. My thought is his upholstery is keeping the seat cushion/pan from sliding back far enough under the frame tabs.
Just my thoughts,
Ray(64BJ8P1)