The pump is a single cylinder steam pump. The 2 pictures below are from the print that came with the Stuart turner castings. It does not have a number or a date, but it is an original ST print.
The upper picture shows the valve chamber. A mystery to me has to do with the 'T' shaped passage I have hand-colored in red, somewhat faintly, on the left side of the drawing. The short vertical stem of the 'T' is the steam-in to the pump. The longer horizontal part of the 'T' shows two very small holes, one on the left and one on the right, drilled at right angles to the longer horizontal part of the 'T'. They look like little black dots on the print. What are those 2 holes for?
The second of the two pictures shows the cylinder to which the valve chest mates.
Sorry about the miserable resolution of the photographs. I can no longer get Photobucket to behave as it used to. Doing a digitized scan of the print might be the right avenue for conveying a clear image.