Yes I believe the 4150s have a different baseplate. Never tried to mix them, so dont know about smaller. Think 800 is smallest/big. The 950 you have may have adjustable idle air bleeds also. You have enough cam and excellent heads. The idle air bleeds are the holes in the primary choketower base. If they are totally smooth they are probably fixed. Anyhow , you can use all of that carb. The pump shot and or secondary diaphram springs will wake up the launch . You will have to experiment with volume and time of pump to match how your engine gulps air when stabbed wot. I have tried to find a happy medium on the idle screws w/ eng temp. Also there is a screw on the bottom of the baseplate to adjust secondary advance which can majorly affect the idle screws and bleeds. Lastly cam intake/ ex overlap on a roller is fatter on lift ,so some raw some fuel escapes with the exhaust around bdcenter.. Hope that is all relevant .....