Hi,
my sort of 1966 Scout 800 has the chrome front bumper, part number 890 033 r3, which according to the parts manuals, was common to the Scout 80, 800, 800a, and 800B.
Way over on the passenger side top flat are two 1/4 inch diameter holes two inches apart (on center), the same as in the center of the top flat on the rear bumper.
More than likely, these were for license plate brackets, but neither the parts manuals, nor the service manuals reflect those items.
I suspect, among various brochures/pictures in our website or on the web, May be found pictures of scouts with those mystery license brackets attached (and/or not).
Hope this helps.