Hi Sam,
Welcome to the forum. I just read all the posts above. I'm not trying to be contrary, but I don't think you will learn much about air-cooled engines from your buddy's AH 3000 that's in your garage. Maybe you meant something other than what you typed, or maybe I read your post wrong, but, barring an engine swap, his engine is water-cooled.
This is a great forum that has lots of collective wisdom on our replica hobby. You'll get lots of advice, some of which you may have even asked about.