Just happened to come across this, even though it's 2 years old. Not sure if you still check up on this, but I thought I'd give it a try. My paternal grandfather's name was David Gibb, also of Allegheny County (more specifically, McKeesport.) I'm not positive on this, but I think he was either a junior or a III. I would have to ask my father about this; he would know more about it. My grandfather died either 2001 or 2002, can't remember exactly. If you think he is a relative of your David Gibb Jr, email me and I'll see what I can learn. I am also trying to research my family tree. It's hard to do because my father doesn't know much about my paternal side. So anything would help me as well.