Missing the EGR spacer? That much exhaust gas erosion, maybe somebody pulled the spacer (and the rest of the emissions control stuff?) and bolted the carb back on. Not normally done, the heat will shorten the useful life of the carb and might cause an assortment of running problems related to overheating the fuel.
For many of these installations, speed shops will carry a blank spacer to replace the EGR piece. I've even seen insulating spacers, to help keep the gas in the float bowl cool. But I don't know whether you might find such a part for a 2-barrel 351W, usually anyone hot-rodding a 351 has found a 4-barrel intake manifold.