There are two improvements in the J/CL/1927 design

The J/CL/1927 design is still too large for the armament, but the design does incorporate two improvements over the 1923 design: a 36 knot speed and twin 4.7in AA guns. The size growth was moderated by lighter weight machinery. I considered using triple 6.1in guns, but decided that was still inappropriate for 1927. The ships do have good strategic mobility and are well-suited to run with aircraft carriers. The US found in WWII that they really wanted faster cruisers and destroyers for that purposed. In the 1920's, prior to much experience with aircraft carriers, the US authorities decided that aviation eliminated the need for speed, and that slower ships were perfectly acceptable. The Japanese tended to want higher speed for cruisers, while the generally accepted 34 knot destroyers, because they wanted a powerful gun and torpedo armament. The original design for the Mogami class is a case in point, as they wanted a 37-knot speed. This is the Springsharp report for the J/CL/1927:

J/CL/1927, Japan Light Cruiser laid down 1927 (Engine 1937)

Displacement:
 10,754 t light; 11,159 t standard; 12,200 t normal; 13,033 t full load

Dimensions: Length overall / water x beam x draught
 651.54 ft / 647.00 ft x 57.00 ft x 20.00 ft (normal load)
 198.59 m / 197.21 m x 17.37 m  x 6.10 m

Armament:
      8 - 6.10" / 155 mm guns (4x2 guns), 113.62lbs / 51.54kg shells, 1927 Model
   Quick firing guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      8 - 4.70" / 119 mm guns (4x2 guns), 51.91lbs / 23.55kg shells, 1927 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      24 - 2.24" / 57.0 mm guns (12x2 guns), 5.65lbs / 2.56kg shells, 1927 Model
   Anti-aircraft guns in deck mounts 
   on side, all amidships, 8 raised mounts - superfiring
 Weight of broadside 1,460 lbs / 662 kg
 Shells per gun, main battery: 180
 8 - 24.0" / 609.6 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.00" / 76 mm 475.00 ft / 144.78 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 113 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 475.00 ft / 144.78 m 19.00 ft / 5.79 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  2.00" / 51 mm

   - Armour deck: 1.00" / 25 mm, Conning tower: 3.00" / 76 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 151,489 shp / 113,011 Kw = 36.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 1,874 tons

Complement:
 579 - 754

Cost:
 £4.064 million / $16.255 million

Distribution of weights at normal displacement:
 Armament: 182 tons, 1.5 %
 Armour: 1,734 tons, 14.2 %
    - Belts: 695 tons, 5.7 %
    - Torpedo bulkhead: 334 tons, 2.7 %
    - Armament: 181 tons, 1.5 %
    - Armour Deck: 489 tons, 4.0 %
    - Conning Tower: 34 tons, 0.3 %
 Machinery: 4,199 tons, 34.4 %
 Hull, fittings & equipment: 4,639 tons, 38.0 %
 Fuel, ammunition & stores: 1,446 tons, 11.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   10,603 lbs / 4,810 Kg = 93.3 x 6.1 " / 155 mm shells or 1.4 torpedoes
 Stability (Unstable if below 1.00): 1.28
 Metacentric height 3.3 ft / 1.0 m
 Roll period: 13.1 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.41
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.579
 Length to Beam Ratio: 11.35 : 1
 'Natural speed' for length: 25.44 kts
 Power going to wave formation at top speed: 61 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  29.00 ft / 8.84 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (67 %):  24.00 ft / 7.32 m (16.00 ft / 4.88 m aft of break)
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 21.76 ft / 6.63 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 190.3 %
  - Above water (accommodation/working, high = better): 152.5 %
 Waterplane Area: 26,445 Square feet or 2,457 Square metres
 Displacement factor (Displacement / loading): 105 %
 Structure weight / hull surface area: 102 lbs/sq ft or 497 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.37
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent