Welcome! Do stick around. As an Armalite fan I would love to see some pics of them. Even though it is a different company now, you might check with Armalite if you haven’t already, to see if they purchased the original engineering drawings of the original AR10 when they purchased the name. It would be pricey, but a machine shop could manufacture or modify something if you can’t find anything original, if you can get the specs. My understanding is that the Netherlands Armory destroyed everything when they discontinued production. Let us know if you are successful. A neat little article, but I am guessing you know all this already.
http://weaponsman.com/?p=3388