Very nice!
I've also heard about the Unryu-class having a successor, named Project G18.
For what i know, the G18 was basically a plan to build a class of light carriers based on the Ibuki, but obviously built as CV from the keel and not as an heavy cruiser conversion; i'm currently drawing Ibuki as a carrier, but it takes a looong time to complete it.
Meanwhile, here is another unfulfilled conversion plan:
1936 CLAA Tenryu conversion:
In 1936 a plan emerged to refit the tenryu class ships as anti-aircraft cruisers, this called for the removal of all four 5.5-inch (140mm) guns, to be replaced by eight Type89 5-inch (127mm) ones, argumented by four trilpe 25mm machine guns; the three funnels would have been trunked toghether to improve firing arcs, masts and superstructure would also be heavily redesigned and toped by two Type94 HA director equipped with 4,5-meter rangefinders; for ASW the plan called for two depth charge throwers and four depth charge chutes to be fitted on the fantail.
1939 cLAA Tatsuta conversion:
In 1939 the same conversion plan resurfaced again, this time replacing the 5-inch guns with the new Type 98 3.1-inch (80mm) guns then under developement; the plan was eventually rejected in favor of the Akizuki class Destroyers.