It's a single barrel Motorcraft carb. Pony carbs has a new reproduction of the Autolite 1100-1v. I'd say at this time this is about as top of the line as it gets. On the outside it looks just like the original but they improved the internals. They ain't cheap, but it's worth it if it performs as well as they say. National Parts Depot also lists them in their latest catalog I have noticed.
The sixes never did idle worth a darned because of the badly designed intake manifold. The outer most cylinders couldn't get a decent air/fuel mixture compared to the cylinders that were closer to the carb inlet. If this was my engine I'd get the best carb available because of the poor intake. It needs all the help it can get.
If you want to rebuild it yourself, just go to autozone and get a kit for a 1100 IV Motorcraft carb.