Nice work Vic.
One very minor point, which is a bit late now, but may help others, or for future builds.
The harness shoulder straps should go over the seat frame, not the seat back. This is because the seat can be adjusted for height, by sliding up or down the frame and then locked as required. If the shoulder straps were over the seat back, between the seat and the top, horizontal tube of the frame, they could become trapped between seat and frame, depending on the seat height.