Mike, that drawing is quite wrong, especially when it comes to the post-1936 extra deck at the bow which looked nothing like that (it actually ran back all the way to the superstructure and was linked to it).
Ryuujou was built in 1933 as shown in WWII44 drawing, fitted with six twin 127mm guns and six quadruples 13.2mm machine guns.
in 1934 wider torpedo bulges were added, the keel was ballasted and two 127mm gun mounts removed, and replaced by two twin 25mm MGs, funnels modified, flight deck widened abreast the foward elevator.
in 1935/1936 the forecastle was raised by a deck and the forward end of the flight deck modified to make rounded instead of squared, some of the lookout post and rangefinder locaded around the bridge area were also removed.
in 1939 the flight deck was taken back to the former width near the forward elevator.
finally in 1942 the 13.2mm machine guns were all removed and replaced with triple 25mm ones.
Other informations are available here:
http://www.combinedfleet.com/ryujo.htm
http://combinedfleet.com/ships/ryujo
WWII44, I've sent you a PM, if you need any hel whatsoever, dont' hesitate to ask me.