You mean this?
It's an imagined ship by the magazine for the following requirements that were considered around 1940:
Resistance to 500kg bombs on deck and turrets, resistance to 20cm rounds between 15000-25000m and resistance to 15cm shells in those same ranges down to 10000m and under the waterline. 35 knot speed, 3 float planes, and an armament of torpedo's (No number on amount listed). She was to be armed with 20cm guns same as the other Class A Cruisers.
The ship itself (named Unzen by the editors) is basically a "what if" based on the limited info that is known.
I came across the scan after I posted the question, so was wondering if this was what you drew.
one of the scans is almost Identical (the other featured the Ibuki, Mogami, the supposed type A, Agano, Kai-Agano and the CLAA cruiser) though it had no text, just specifications, and did not featured the center fold of the pages (possibily it was cropped and fixed).
However, this means I can at least delete one ships from my "search more references" list.