Regarding the front seat rear sheet metal: The sheet metal panel that I have has an angle iron attached to the bottom edge (from side to side). Is this normal, as it looks like it is functional? Also, the bottom edge of the sheet metal has small holes as if it was nailed to something, possibly a wood cross member. Is there a wood piece that goes from side to side at the bottom of this seat panel, and if so what size should it be?
If you're referring to the front seat back panel that the spring attaches too, there's a piece of wood that goes in the bottom for the upholstery to nail to. One came with my kit, but was nowhere near big enough so I made one about an inch square and made it long enough to fit snugly inside. I think mine was 31 inches or so but I can't remember. Just measure and make one. You can see it in this picture: if you look close it's just behind the plywood.