As you mentioned, adjusting your idle mixture screws will help a lot with the idle reading. I would try leaning them out a little (turning them in). 5 turns out is a good starting point for my carb and a lot of other guys with the Carter, but try to adjust to lean best idle and then stay there instead if backing off the recommended 1/4 turn, or just back off 1/8 turn until you pass emissions. The factory setting for the idle mixture screws was closer to 1.5 turns out, but I hit lean best idle well before that coming in from 5 turns. You'll know you're making a difference just in the richness of the exhaust smell as you go. At 5 turns out, the exhaust fumes are probably so rich, it's burning your eyes.