As someone who tutors figure- and nude drawing in uni, I can tell you the proportions are overall fine. They are actually very realistic. The hair volume might give you the idea that the heads seem a little large or simply the fact that fighting game characters, especially men, are usually portrayed with the idealistic/heroic 9 heads per total height instead of 7 and a 1/2 to 8 heads of normal grown-up human beings.
Shinkiro, the artist, was back then known for his almost photo realistic illustrations. He did also work with photographs