No one I know of really makes repro small parts. Nodak does stripped uppers, stripped lowers, and charging handles. Parts kits are the only real source for the correct small parts and those kits, for cheap, dried up some time ago. You can get individual parts off of gunbroker if you are willing to pay. Your cheapest option is most likely getting a complete A1 upper with all the parts still installed.
Vietnam era M16a1s are all grey. As they were rearsenaled some were anodized black but retro builders aren't interested in that look generally. They want the Vietnam era correctness.