Disconnect the secondaries, or put in a real stiff spring. Now you're working with just the primaries. Establish what vacuum you run at idle, cruise and mild accel and I will help you with a power valve choice (key to fuel economy and power balance!). To do this, run a vac hose through the firewall into the car, connect to manifold vacuum. Have a buddy monitor as you drive (hint, full accel will be zero). In the meantime start leaning out the primaries until "mild" acceleration and cruise at 50+ mph starts to hurt (do not pound on the car when doing this test!!). When you notice a slight loss of power on mild accel and cruise isn't smooth you're too lean, bump up the main jets 2 units to re-establish smoothness and you're on!

 

Complete this test, and provide vacuum readings and i can provide the right powervalve selection and the right secondary jets. Final lesson, fine tuning the accelerator pump.

 

In case you wonder about my experience and credibility, I have an Edelbrock 650, holley 670 avenger, holley 800 double pumper, holley 600 vac sec and a 650 demon. All of which I have dialed in well to suit their individual strengths on my engine. At 46 years of age, I am far more at home with a carb than a standalone. Next project (not this year), twincharging using a carb and dizzy......

 

Right idea grasshopper, but tune the primaries first and the secondary jet choice is cake!