Whats the correct carb for 69 340 4 spd

Ok I has found someone that has a #4611 carter carb for me. He says that it is correct for my 69 340 4 spd, but in my parts manual as well as one of Goviers books, it shows #4611S as being the correct one. apparently the difference between 4611 and the "S" is the jets and metering?? Simple cheap easy fix?? I am not a carb guy, and wondering if it is worth putting it in my car, as I want a little more lump in the 340 than what was factory. Nothing drastic, because its basically going to be restored ot original, except for maybe pistol grip shifter and the extra "lump". Its a convertible, so I dont wanna twist the $hit out of it. Sorry for being long winded.
Is or will the orig carb going to work with the extra "lump"??
Can the changes be done (by a carb guy) easily and economically to change from 4611 to 4611S

Thanks
Steve