For the purposes of any future ban? I have no idea. Depends on what our elected idiots decide to do.
Personally, I'd take a lower, put in a LPK, attach a stock and a complete upper, and take a photo with time/date stamp. There's no way to prove it conclusively, but that's pretty solid. Maybe have someone "witness" it, if I were worried about it.
As it turns out, I have a couple of stripped lowers, but I have the parts to assemble them. I'm just gonna put them together now (no reason not to) and not worry about it.