Design A-121 was most likely a modified fast version of A-119 with extra length and engine power added to reach the desired speed of 59km/h or 32knots. The next variant A-122 is very similar just longer by 14 meters. As I did not found any drawing for this particular proposal I've used a modified main armament layout of A-122 where I've changed the position and angle of the 3rd turret as well as the aft mast.
The design had the following characteristics:
Dimensions: 252,98 (pp) x 266,7 (wl) x 269,14 (oa) x 29,57 x 9,14 meters
Displacement: 40.600tons (standard)
Armour: 229mm Belt inclined at 25 degrees, 76mm Deck, 51mm at Machinery 76mm at Magazine Slopes
Engines: 150.000shp Gihon Steam Turbines, 4 shafts
Range: 10.200km at 30km/h (5.500nm at 16knots)
Speed: 59km/h (32knots)
Armaments:
5x2 410mm/45 Type 3 / 3rd Year Type Cannons,
20x1 140mm/50 Type 3 / 3rd Year Type Guns,
4x1 76mm/40 Type 3 / 3rd Year Type AA Guns,
4x1 53cm Above Water Torpedo Tubes
Data table:
https://iiif.dl.itc.u-tokyo.ac.jp/repo/s/hiraga/document/62342cb9-e432-49c6-b8da-767bbf081fed#?c=0&m=0&s=0&cv=5&xywh=1362%2C716%2C2766%2C1650
https://iiif.dl.itc.u-tokyo.ac.jp/repo/s/hiraga/document/d059f655-21b8-4530-8979-ce9ac0733c10#?c=0&m=0&s=0&cv=23&xywh=1503%2C730%2C1650%2C2766&r=270