Interesting! The Factory Assembly Manual shows the filler panel (3701226) for a 1954-55 without dimension and location for the license plate bracket (3705102). I guess you had to drill your own? Another issue is that if you want fog lights, the passenger side would cover the plate so the plate should be mounted in the middle?
The filler panel I have is different on the right side where the license plate bracket goes. The raised area is smaller and has the holes for the bracket. I drug it and the front bumper out of a wrecking yard in Nebraska, and I believe it to be original. It was found with the bracket bolted to it.