I have a 1969 runner 440 4spd. no air. It came with an 850 double pumper witch just seems to be overkill. I live at 6100ft of altitude(does this matter in selecting a carb?) I have no idea what it has for a cam or pistons but it seems fairly mild. It's a C440(1967). It has a Weiand dual plane manifold and 3.23 gears in the rear. Can this 850 be properly jetted? It seems to be running waaaaay rich. Any suggestions for a new carb size for this combination? Thanks, Joe.