I have a metal coil box and a number of reproduction parts that I purchased years ago, but never assembled. I sat down with it this morning in order to "dry fit" a few things and discovered that the rear wood panel will not slide down all the way as it hits a raised lip at the rear bottom of the box. The wood is a reproduction piece. Is it supposed to have a groove cut along the bottom edge in order to slide over the lip?
As is is now, the wood cannot be moved all the way to the rear and the coils sure aren't going to fit that way!
If the wood is made correctly it will have a groove across its entire bottom edge that will slide over the metal lip. There is an issue with the earliest boxes in that the metal lip will not allow clearance for the two round head wood screws that hold the rear panel to the bottom panel. In that case you must file a pair of small notches in the metal lip to allow the panels to move down into the correct position. Ford addressed this issue later on, making the metal lip narrower.
Personally, I recommend getting a set of Fun Projects' coil box plastic. Not only is it water proof and short proof, but it is made exactly to the Ford prints, which makes assembly a lot easier. I have restored many metal boxes using it, and I speak from experience.
I've used Johns new plastic parts, and they are perfect. The problem with the originals is, when they get wet, they short out.