carb help
What might have happen is you used the wrong gaskets under the booster. They give 3 or 4 but only 1 is right. You need to match up your old gaskets with the new ones and throw the rest away.
A rebuilt carb should only need the idle screws adjusted, maybe a metering rod changed. They will want you old carb but if you can mike the rods so you know which size you have it help.
Or get a 2 bbl 350 Holley carb that just uses jets and no rods.