No way the FSB is A2 since A2 has a .750" diameter for the gas block journal.
+1 for getting an original Grey Colt Charge Handle, a correct selector, mag release button, and your call on the A2 front sight post. If it were mine, I would Cerakote to match the upper and lower, after filling in those dings.
When installing bolt catches, not only do I use multiple layers of thick tape, but the O ring on one of my larger punches. I keep the O ring down near the tip of the punch, to guide it along the side of the lower so it can't impact the receiver where yours is dinged-up.
You're very lucky that you got an original ejection port door.
You also need a real lower receiver extension tube and maybe a trigger guard, or have yours coated grey. Your type D stock looks great from here.