Get the tuning manual for the carb from Edelbrock. The main jets and metering rods work in concert, so it isn't as simple as just changing the main jet. The manual will tell you what jet and metering rod to change.
Having to pull that much jet out of an ede carb is not a normal situation. One thing that I like to do, especially on street driven cars, is disconnect the secondaries and tune only the primaries. Once the primary side is right, reattach secondaries and tune that side.
Something is causing the rich condition, high fuel pressure or something. Is there any fuel dripping into the carb bores?
