I know I'm violating two important social boundaries here. This is a question about a vintage gasser, so please excuse me. But, there are a lot of good diagnosticians who post here, so I'm expecting stellar advice, even though it's not a diesel question.
The last couple of times I've gone to start my 74 Olds Custom Cruiser, carburated 455, it's had a pool of gas on top of the intake manifold. A cursory examination revealed that it does not look like the gas line to the carb is leaking. What could be causing this pool of gas. A stuck float? How is the gas getting outside the carburator rather than running inside the intake? It may also be running inside the intake because it acted as if it was flooded when I tried to start it today. Any insights appreciated.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13