No chunk missing. This is the way the venturi on a Tillotson carb is formed. But you do have a good deal of varnish and gunk inside the carb. Looks like the car was left unused for some periods of time and whatever gas was left in the bowl slowly dried up leaving the residue and ridges around the inside of the bowl.
Your leak may be coming from junk in the float valve holding it partially open.
The overall inside condition of the carb could also mean the gas is creeping up the sidewalls and leaking out the gasket between the upper & lower carb housings. There are those who will say this can't happen if the float valve works correctly, but it does.
A major problem with Tillotson Carburetors is that the upper housings tend to warp in two places. The flange where the carb mounts to the intake manifold warps due to overtightening of mounting bolts and due to the close proximity of the carb to the exhaust manifold. This explains leakage there during startup when engine vacuum is "pulling" gas up the throat of the carb. The other warpage is on the bottom rim of the top carb body where it mates with the top rim of the lower carb body. This allows gas to leak around the gasket between to carb bodies. The warpage at the flange can be repaired by filing it flat again. The warpage at the mating rim is a bit more difficult and not always easily achieved. If the gap between the two bodies is not severe, sometimes a double gasket will alleviate the problem.
Then, there are the normal reasons for carburetor leakage ............... bad float valve, incorrect float level adjustment, ........ sticky float (as you mentioned) ............. some of the above, all of the above ?????
The rest is up to your expertise in carburetor repair or the option to replace the carburetor.
Good luck. Bob Bader
