ORIGINAL: mlees
The US industrial might was HUGE. Historically, the majority of the production went to Europe, and as lend lease to other allies.
If the Japanese had landed on Australia, I would like to think the US would have diverted ETO bound stuff to the PTO. I feel that it is reasonably safe to say they would have done that had the Japanese landed on the US west coast.
Just how much the US player should get in equipment and manpower allocated to the PTO, based on how well the Japanese player does in a particular game, is speculation at it's most enjoyable (and more suited to "World in Flames"), but not fun for the IJN player. Keeping it at the historical levels is well enough, as it does not penalise the Japanese player for doing well.
The numbers I put down weren't total ... they were just for the Pacific. Even though 70% was supposed to go to Europe and only 30% to the Pacific, as far as the Navy went 70-80% of the US Navy was in the Pacific until VJ-Day.
The US scared the living crap out of the British who wanted the US to sit on our hands and do nothing in the Pacific until they defeated Germany and then, according to a proposed British plan go after Japan and finally invade Japan by 1948. The US didn't and did the one thing that military experts shy away from: fighting a two front war.
If you want "historical" then you have to deal with the fact that the US industrial base outclassed Japan from day one. During the course of the war the US built more SUBMARINES alone than the Japanese did in ships of all classes.
To be "historical" the only options for the Japanese are to strike out and build a defensive perimeter and then dig in for the inevitable onslaughts and just buy time. That's the only option the Japanese had after Pearl Harbor - the irony was that if they had attacked the British and Dutch and left the US out it's very unlikely Roosevelt would have had the public opinion to be able to get the US involved.