ORIGINAL: Andrew Brown
As I mention, my preferred ("safe") starting position is to retain what we have already.
Perhaps that is the root of the "Problem". The economic model used stock WitP as the basis line. I would suggest that perhaps the outputs of HI and LI may be too generous.
Read an interesting quote last night...
In order to supply the steel necessary to produce combat and tracked vehicles, it was necessary to sharply reduce motor vehicle production. In order to raise the level of air ordnance output in 1944, when the aircraft drive reached its peak, it was necessary to sharply reduce steel allocations for Army ground Force items such as artillery, ammunition, tanks, etc. In order to award the major priority on basically limited steel supplies to merchant shipbuilding, the whole ordnance program, though it expanded substantially, had to be held to levels which did not meet scheduled plans of production or military requirements.
p.233
Japan's Economy in War and Reconstruction
Jerome Cohen

For my MOD -
I would suggest a COMPLETE re-evaluation of the economy. For example examine the HI requirements to produce what the Japanese historically produced. IIRC players are capable of creating huge stores of HI points, which obviates the need to transport in resources late in the game as the Japanese player can subsist on the HI stores created earlier in the game.
I do not know for I have yet to study the numbers ... and this is just a theory...but perhaps a reduction in the At-Start numbers of HI Centers and/or a reduction in their output would be in order.
The work required would be intense...but essentially involves the following --which is just the beginning framework and is not thought out entirely yet:
1. A month by month examination of the HI points required to produce the historic Japanese reinforcements.
2. A comparison of the requirements of #1 with the output generated by the current HI Centers.
3. An estimate of Total Japanese Daily Supply Requirements. (perhaps the Tracker Heads can shed some light here...)
4. Examination of the supply produced in the various map sub-regions.
5. Determination of Japanese historic supply production capabilities.
6. Re-define the meaning of HI centers and LI centers - HI centers representing the part of the economy used to generate HI points that are used to build war material...LI centers being the part of the economy used to produce items consumed by units.
7. Factor in the "hidden" Civilian economy as is currently done by requiring HI centers and LI centers to consume more resources than their output.
8. Set the HI and LI requirements such that Japan is required to import c. 25 million resource points per year at start. Need to look at stockpile numbers for coal and iron to determine how much of a surplus is generated if any early in the war.
9. Set outputs to mirror / emulate the historic capabilities.
ETC ETC...