I think most of the ones you mentioned have been covered. I would agree that the Japanese types are scarce, Nambu, Arisaka etc. They may be more difficult to make but I think the MGs would really fill a need, Browning .50 cal., the old U.S. water cooled model with the barrel jacket, etc. You might also look at what uniforms and other equipment are available and plan accordingly.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken