That looks great, Matt!! I forgot about the 3PO kit. I still have most of my Vader kit with the glow-in-the-dark eyes... but, without his right arm and lightsaber. Perhaps he lost a previous battle with a Jedi and was on his third arm by the time ROTJ rolled around. LOL!
I know that arm kept falling loose and eventually broke off at it's hinge. I might have it somewhere, but since I was a kid when I built it back around 1980, it wouldn't help the model much. I think Darth is a lost cause.