Thank you very much for your friendly posts, Aaron, Gnomey, Lucky13 and Wayne!
I-400 class sumarines left a lot of photographs taken by the US Navy but little original documents of IJN.
So, I was not interested in modelling them at all though I knew there is a good operation manual of I-14
whose basic structure is very similar to I-400 class.
A few weeks ago, I came across a very historical record of I-402, titled "Delivery List of I-402 dated October 5th, 1945" at JACAR site. It begins like this -
Delivery List of I-402 dated October 5th, 1945
============================
1. Completion date: July 24, 1945
2. List of Main Terms
a. Vessel type: Submarine
b. Displacement(standard): 5,284 tons
c. Length/Beam: 122 meters(400 ft)/9.8 meters(32.13 ft)
d. Draft(average): 7.46 meters(24.46 ft)
e. Speed: 18.9 knots(surfaced)
6.8 knots(submerged)
f. Range: 33,000 nautical miles at 12 knots surfaced
g. Power plant: 4 x diesel engines
2 x electric motors
3. Summary of present condition
Classification*******Item********Quantity********Present condition
========*******===*******=====********===========
Hull&Equipment*****ditto************************Fully equipped
*************Heavy oil tank*******31 tanks
For more details, I will make up a translated list in the excel format on the other day.
There are all equipments, fuel, oil, armaments and even foods in details on the list.
Original copy is attached here for your quick reference in pdf style.
.............I have found out no reason not making the I-400 on my CG.