Jumping in as this is a great opportunity to mention a useful technique: We know the board is fundamentally a grid of holes with .100" spacing, and there are good pictures of it taken fairly straight-on, so it should be easy to measure any feature of interest by proportion in a graphics program.
From dividing the spacing of 10 holes, it turns out that the back of board picture seems to be 300 dpi - could be a lucky accident or careful adjustment, but it raises the possibility the picture was made with a flatbed scanner rather than a camera.
From that, the diameter of the mounting holes appears to be .12" - not quite as accurate a measurement as you could get directly from the board (since there's some judging of edge shadow), but fairly close.
This is just under an eighth of an inch, and within measurement error over 3 mm. A 4-40 machine screw should pass through cleanly, and a 5-40 would thread in loosely.
Given the 300 dpi, you could probably print out the picture on thick paper and use it for mechanical fit testing - just measure the grid in both dimensions to verify the scaling came out right.