You have about half the CFM you need, so you're going to be fighting a losing battle. That being said, the over rich condition is probably due to fuel pressure, not jetting. Webers only need about 2 PSI of fuel pressure, and if you're running an original type mechanical fuel pump it can go to 4-5 PSI or more, depending on the spring the manufacturer chose to use in the pump. The overpressure pushes the needle valve in the float chamber off its seat and causes the carb to run one of two ways- - - -rich or REALLY RICH! If you insist on running the wrong carburetor, install a good adjustable fuel pressure regulator.
Jerry
