A serval is meant to have a broad power band which is why people dont understand why you went get it drag ported. People get cubs if they want a top end/drag set up. You could of got a cub and came out cheaper/better in some cases. People say single carbs dont do well on top end and arent meant for drag racing. 2 into 1 is seen as low end set ups which is opposite of what you want.
So in general, keep two carbs. Stock carbs will work. A lot of people do 35's.