It just depends what your engine set up is.I have one on my series 2 big block motor with a Casa 210 top end and clubman exhaust.I have a 130 main jet,48 pilot jet and a 50 choke jet,this all runs through a drilled airbox.A standard GP200 uses a jetex with a 118 or 123 main jet,depending on the type of exhaust used and a 45 pilot jet and a 50 choke jet.
The size of the atomiser and slide differ dependant on wether you have a 150 or 200 carb.The 150 carbs have a 5899-4 atomiser and a slide with a cutaway in the back,but a 200 carb has a 5899-2 atomiser and a plain slide(no cutaway)