First off are thre points & timing set right? If it doesn't have vacuum leaks it might be the float level is too low. I would take the top off the carb & check the float level & metering rod adjustment. You could raise the float level about 2/32. Try screwing the idle jet out about 1 turn.
A better discription of the symptoms would help, like does it idle without the choke? That carb was not standard on a 66 engine, but it should work good but needing a little tayloring. Most reman carbs are not right. You might think about sending it to a carb specialist like Carbking.
