The sight you have pictured is an early No 5 with a single #12 mounting screw and was only used on the very early 1919 NRA's. Later No 5's added a second #5 size mounting screw spaced about 1.50" back. That's not a very sturdy sight and requires a taller front. I think the No 10, which mounts with the same two different size screws and the same hole spacing, would be a better option and I see both the No 5 & No 10 selling for about the same money. I think the No 10 would also require a taller front sight.

The no 5 sight was only used for a short time after the introduction of the 23-D. The 23-D first shows up in a Jan 25, 1932 price list I have and is not in a Jan 15, 1931 - the No 10 sight shows up in a price list from April 1, 1933. The 23-D's made after about March 5, 1936 would be drilled & tapped for the No 15 rear sight, it mounts with two screws the same size with a .875" hole spacing (I think #8's). The #10-36 (or possibly 3/16"-36) & #5-48 Mounting screws for the earlier sights can be hard to find.