Allways had a liking to these, and as Bill said, the screws do seem too small.
Also I would suggest doing a new 3"/50 mounting as it was a single, as was the 40mm mounting aft.
I also wonder as to the difference between the two versions - to me they look the same
apart from the caption that says 1988.
For the 3"/50 singel, ask acelanceloet. but they have ... same look! And the 40 mm mounting aft is a Bofors single 40mm in a box! from acelanceloet parts...