Wise choice.If SU's are "correct" to begin with,once they're set,you shouldn't have any "issues" with them.Anytime you make fuel/air mixture take 90 degree turns,it really,REALLY isn't a good thing.THat's why Holleys don't belong on inline engines.
I'd agree,but then we'd both be wrong.The thing is a door stop.THere is NOTHING that thing can do that a DGV can't.ANd the DGV or SU's will be a superior carb to any quad you put on it.Plus get better MPG's while doing it.
Assuming highest case,you really don't want to go higher for the street.Do your calculations FIRST!Results might dictate the path you'll travel.Too high and all you have to do is dish a couple CC's out of the pistons if the motor is apart.
Larger ports(increasing runner volume) will move the powerband upwards.You want to be real carefull about hogging them out as the bottom end will vanish.