Good question if we think of it from a different perspective. I'm not a fan of single carbs for twins or twin carbs on 4s unless the crank is re-phased to suit and that isn't either practical nor a good idea in this case.
CR carbs are the ticket but they are not cheap and unless you are racing or have tons of surplus cash, there are other options. In the day, a set of 26mm (1") AMAL Concentrics were the way to go. Maybe there's a similar set of say Kawasaki KZ650 carbs that would work better than stock carbs. PJ probably has some ideas on that.