RD, you are doing great, and so is Zap. You just have to be very, very patient, and focus on the positive, which it sounds like there is plenty of. It took eleven months before Uncle Fred was really "normal" and even then it is relative.
I don't think he will ever adjust to men approaching him and trying to pet him by putting a hand higher than his head. Of course, now instead of cowering he howls at them, and backs off. He just kept getting a little better, day after day.
Like in the movie "What about Bob?" it's all about baby steps.