The cast Bofors gun will have to be assembled from the three parts in the deck hardware kit.  You can epoxy or super glue the together.

Study the mast detail drawings. The mast itself is made from a 6-3/8" long piece of 1/8" dowel, wrapped with cheap typing paper to give three different diameters. First cut a piece of paper in an accurate rectangle 4 13/16" high by about 6" long. It is important that piece have good square corners. Put a piece of ½" scotch tape on one of the 4 13/16" sides so that only half of the tape width is on the paper. Trim the tape even with the 6" side of the paper. Place the paper on a clean surface with the sticky side of the exposed half of the tape facing up. Place the dowel on the paper parallel to the tape, one end of the dowel should overhang the paper ¼" to form the stud at the bottom. Carefully roll the dowel onto the tape to secure the paper to the dowel. Roll the paper tightly onto the dowel until you have built up the diameter to 3/16". Now apply some "Zap" or "Hot Stuff" to the paper and dowel to secure it. Trim off the excess paper with a razor blade and sand smooth. Repeat the process with a piece of paper 2 9/16" x 6".

When dry sand the tapers at the top of each piece of paper.

Carefully drill the mast for the 1/8 dowel cross yard. Cement the yard in place then add the rest of the bits and pieces. The (d) labeled parts on the drawing are the small cast mast lights in the deck hardware kit. The two large mast lights in the hardware kit are cemented to the platform on the front of the mast just below the yard. The anemometer on arm (c) shown in fig. 7 is a little fiddley to carve but really looks great on the model.