I've played quite a few 20mm. wargames around WW2 in the far east and even ended up converting a couple of A12 Matilda II tanks into Aussie "Frog" flame thrower tanks.
I'm still working on a A13 II Covnanter bridge laying tank and the Aussie Sentinel tank models.
I do prefer playing the Japs though (well someone has to in a game) as the morale structure is always more favourable, some of the tanks are quite good compared to the hand me downs the Allies received from the middle estern theatre, anti-tank weapon, especially the infantry ones, are bizare (Luinge Mine or Cherry Picker anyone??) plus I can use grenade snipers.
It is just that playing Japs allows me to put up a formidable defence to my opposing players with very little in the way of equipment than I could if playing a defence with Allies. Make for a good game as well.
Best moment in a WW2 Jap versus US game..... taking out two of the four M4 Sherman the other players had in a game with a Type 1 tank destrioyer a minute after they claimed that the Japs, quote, "Don't have any decnt tanks that can take out an M4!!"
Another player took out a thrid M4 the on the next turn with a Lunge Mine (HC bomb on a pole porpelled by a running Jap soldier) and the final one was finished later with a Type 3 Ceramic Thermide Grenade.
Needless to say, we won that convention game!!
I think that you're in for a tough war for the first part, at least, due to limit resources and manpower, until Allied war production picks up.