Yes, I agree. Good effort Kevin!
The way I established the shape around the light was to find centre. Draw the hole and the O.D.,drawing it with a compass.(top 180 degrees)
With the compass still set the same, on a line through the horizontal centre, blend the missing bits (quadrants)each side...... Underkistumble?
Kevin your measurements confirm that the earlier plate with two lights fitted was otherwise the same size,