When I say 2 numbers I am talking jet sizes not AF ratio numbers, probably going to be more of a dog if you get a that much leaner.

Carbs just run rich on decell, I don't know much you can do about it, perhaps you can get an air valve like a reverse blow off valve to open when vacuum gets high and let some air in. This is why the NASCAR cars (before EFI) would always be dumping fire out the exhaust when they let off to go into a corner. Now they can shut off the fuel completely on decell and help MPG... not something easily accomplished with a carb.