Your classification claim and your insistence that the mixed 7/12mm load out is the sole and most prevalent is directly contradicted by:
A Research Study by Richard L. Dunn (c) 2002, 2004: Nakajima Type 1 Model 1 Army Fighter (Ki 43-I) Armament -- A Reassessment (part 1)
http://www.warbirdforum.com/rdunn43.htmas well as the less reliable Wikipedia article on the Ki-43
http://en.wikipedia.org/wiki/Nakajima_Ki-43What non-Americanized English source are you using which completely negates this comprehensive research?
Abstract
Popular works on World War Two history, such as Dr. Rene J. Francillon's tome Japanese Aircraft of the Pacific War, generally state that the Japanese Nakajima Type 1 Model 1 fighter (Ki 43-I), Hayabusa, was produced successively in three versions ko, otsu, and hei (Ki 43-IA, -IB, and -IC) armed, respectively with 2x7.7 mm machine guns; 1x7.7.mm machine gun and 1x12.7mm machine cannon; and 2x12.7 mm machine cannon. It is generally reported that the version with two 12.7 mm machine cannon (Ki 43-IC) was the major production version.
This paper presents evidence that while the twin 7.7mm version and twin 12.7mm version were introduced prior to the mixed armament version, the latter was introduced very early in the production run (prior to the outbreak of the Pacific War), was undoubtedly the major version of this aircraft to see action, and examples of operational aircraft with the alternative armaments are both relatively rare and may well have been retrofits. However, due to the ready inter-changeability of the two weapons types and absent direct evidence, the exact number of production types and retrofits could not be determined.