Either of those carbs are more than that build can use. A 650DP would be a better choice as would the 670 Street Avenger.
A single plane would only be an advantage over the air-gap if you were turning in excess of 6000 rpm a lot. Same with the bigger carbs they may give you a poney or two in the upper reaches of the rpm range but will be a definate liability in regards to throttle reponse and driveability below 5000 rpm.