Won't start

view_from_valve_cover.jpg view_towards_valve_cover.jpg Here are pics of the carb base from a couple different vantage points. Top image is from the perspective of the valve cover. Bottom image shows the blocked off vacuum port on the other side.

The engine idles a bit rough, so I may have a vacuum leak somewhere, but I haven't started trying to isolate it. Oh... While I'm on the topic of potential vacuum leaks, I have a problem with the back top bolt on my intake/exhaust manifold coming loose, and I constantly have to retighten it. It's currently got a white residue around the one bolt hole (coolant?), and I had to replace the gasket a few months ago because it had burned out back there. Seems to diesel when I let that bolt loosen too much.