I am getting ready to replace the carb on my 305. I only use my Jimmy for on-road use. What would you guys recommend? How many CFM for decent gas mileage? I read that the stock carb is over 750cfm, but I am thinking about something under 600? The current carb is computer controlled, but it isn't working. It runs super rich. The Jimmy is California equipt with the high altitude package. That doesn't do me much good here in Kansas. Suggestions?