Unless you're concerned about the numbers on the mounting foot of the base, consider using a 4966S AVS carb. They were used on the luxobarge 440 engines, which were built in much bigger numbers than 340 cars. The 4966S is relatively plentiful and cheap, and looks nearly identical to the correct numbers carb. An additional benefit is they flow more CFM, giving you a performance upgrade. I believe
@GTX JOHN really likes these carbs. He's a been there, done that guy, so always listen to what he says.
The biggest drawback of the 4966S is the poor availability of jets and metering rods for tuning. That'll be the same with any AVS though. I've collected some over the years, paying whatever asking price was. I now have enough for nearly three Strip Kits. If you go the AVS route and need jets and metering rods, send me a PM. I'd let some go, but at the price I'll be asking, you'll probably be better off buying a new AVS2. Scuff the shine off, and it'll take a sharp eye to tell the difference with the air cleaner on. Mancini Racing just sent out an email showing the reproduction air cleaners available. They look pretty nice. Pie tin engine ID plates still unavailable new for now, though.