I've used all the carbs that came on these engines and never saw much difference in power. I've had several and the one I have left has the older square aluminum carb with no fins and the low speed needle inside the throttle arm. I also have a Perry pumper carb and pump but I didn't see any noticeable increase in rpm.

My favorite of the ones I've used had a Perry carb on it but didn't make any more power.