Nothing you ain't prob already thought of (& tried) but I'd do the basics: float level/vac leak/jetting/accel pump (for the hesitation). I'm assuming you are on ported vac. It was good b 4 & no ch ex for the restored AVS? OE avs's are emission carbs & there was the constantly changing stringent emission std's that were put on Ma (& the others) back in the late 60's early 70's but they can run like a scalded cat. There's a serious prob somewhere that is making it hesitate and that may b something other than a garden variety weak AP shot (I'm sure you've checked) & if so it is screwing up your AF ratio & killing the mileage. Holler when you find something EDIT I'm assuming the springs are keeping it on the "cruise" step(s) at the vac level you are maintaining at 3100 rpm