Check and make sure there are no severe angles in your drive train. Try and imagine a smooth straight transition from tranny to drive line to rear end. My ujoint angles were way off and I had vibration and a loud knocking sound after lowering and a 5speed swap. You might need some tapered lowering blocks?
Looks good. Did you blast or use paint stripper prior to paint?
That's one of the colors I'm considering for my 4 door project. Got a pic of the paint can?