OK, I finally figured it out, and got a really good generic head in Blender, with a high-detail texture on all sides mapped onto a low-poly mesh. This model has a vertex count of only 109, and edge count of only exactly 300 (not intentional, just a coincidence).
Adding scalp hair and varying the features should be rather easy - at this point, now that I know how to do it, it should be easy to make lots of different heads now.
I'm going to separate this .blend file from the soldier body models, and upload it soon, just as a backup.