2100 lean

I am working on a 1971 LTD 351W with 11,000 miles. This car is mint. From sitting the fuel tank, sender, filler neck and fuel pump were replaced due to rust. I rebuilt the carb due to being very lean all around. I cleaned the carb very well using pro strength carb solution allow the carb to soak for a few days and blew it out with compressed air. After setting the timing, dwell and carb, the carb is still lean at idle and in the transfer circuit. I have the mixture screws out about 5 turns and they no longer will richin up the mixture. The engine has no vacuum leaks. I took the carb back off and looked at the booster venturi and the idle siphon tubes looked like they were a little closed up on the ends so I took a very small drill and made the openings round again. Still have the same problem. What else can I do to fatten this carb up? I also made sure the float is set properly and I have rebuilt about 100 carbs in the past so I know what I am doing. I thought about decreasing the idle air bleeds to richin it up a little? I am at a lose.