1985 GMC Safari won't start

I recently was given an 85 Safari. It had been sitting for well over a year. At first it started with no problems. While driving on the expressway it would start shuddering and you could smell intense gas fumes. When idling at a stop sign it would start shuddering and sound like it was going to stall. Finally, when I started it, it was 'bucking', smelt of gas, and black smoke was puffing out of the exhaust. Now it won't start at all.
It has a gas smell huge as the engine turns over and floods. There is spark, all the spark plugs are new and do not smell or have gas on them. I've never run into a vehicle with a carbuerator that won't start when there's fuel and spark present. Can you give me possibilities as to what's wrong with it? As well there is a new fuel pump in it since we thought at first that could be the problem.