Plugs out; carbs bad, but what kind of carbs?

My socket set only has a 5/8" spark plug socket, so off to the auto parts store to get an 13/16" version. Minutes later, and the plugs are out:

They're not in terrible shape, but not great either. Time to look into new plugs and wires too.

While under the hood, I took a look at the markings on the engine block. They didn't come out well in photos, but here they are:

I know that one of these is the engine serial number, but you can tell that there is 60+ years of grime making things tough to make out. Once Big Red is road worthy, part of the plan is to take a power washer to the engine to clean it up quite a bit.

Finally, I took some pictures of the carburetor. I can't tell which of the two models (Holley or Zenith) that were offered on the KB-6 it is, so I'll be offering these photos to the fine folks at OldIHC.org to see if they can help, and there by help me find the correct rebuild kit.