Basically the computer is going to control the primary metering rods. The mixture control unit holds the metering rods down in the jets leaning the carb out for Idle. With out this hooked up you will run pretty rich at and just off idle. You can pull the aluminum plug from the air horn and play with the primary enrichment screw, but after a couple of weeks you'll be better off getting a carb designed to run without the computers assistance.
I suggest that you consider making a purchase of a new carburetor. Edlebrock makes a direct bolt on carb that would work great for your situation. I'm sure Holley has some too, I just prefer the edlebrock.