The pics didn't turn out very well. Hard to show the measurements without the angle the pic was taken at changing them. So here you go:
The plate is
Length = 28 3/8"
Width = 6 1/4"
The 1/2" holes are roughly 27 2/8 x 4 3/8" on centers.
The viewing rectangles where the LED shines through are in from the edges roughly 4 1/2" and down from the top/bottom roughly 1 1/4".
I think the plate I have must have been one of the first and/or cut by hand because things aint exactly square or centered. I'm sure the new ones are much better than what I have.
Hope that helps!