Very nice work, I wish I had your welding ability.
Along the same lines as the anti-squat discussion for the lowers, I've found that the frame mounts for the factory uppers needs to be higher for lowered cars. This is even more of an issue if your UCA mounts on the rear end housing are higher than stock, which it appears they are. It would be a shame to do all of this work and not optimize the rear suspension geometry.
I thought about making a few different adjustment settings where the upper arms bolt into the frame by making three different hole positions. Just didnt get that far yet.