I think this is a consequence of most modern sport engines having too large a carb for the revs normally turned. The correct fix of course is to sleeve down the barrel like Super Tigre do when they use the same carb on different sized engines. I see nothing wrong with leaving the barrel at whatever opening provides no more revs but the main needle would most likely need to be retuned because there's then a higher velocity of air flow through the barrel which will give better fuel draw. The mass of air flowing through will still be the same because that's all the engine can pump. Set the barrel and tune the high and low speed mixtures and go for it.