i have a 350 chevy in a 59 Willis panel. The engine has a ca in it not sure what it is exactly , it has a larger race carb on it right now. I had the engine Dyno tuned but it still seems to run rich ( the tuner said it was leak) but you can smell a lot of gas when idling. Currently getting about 8 miles to the gallon on this. The tuner re jetted the carb and said it was running lean...... my question is do I need to put a smaller carb on this and if so what's best , size. Will u see better mileage?