Adjusting pump shot

You've got the right port. Attach your vac gauge to that port. There should be no vac at idle, but it should come on quick as you advance the throttle. Also check and make sure that the vac diaphragm (pot) on the distributor is actually working. If the diaphragm springs a leak, you wont get vac advance at all. I check the vac pot by applying vac to the hose that leads to the pot, with either a vac pump or suck by mouth. If the RPM's increase, then the pot is functioning.

If all thats working fine, then I would assume its at the carb. The pump shot on a Holley is adjustable at the throttle arm. If you look on the side of the arm, there should be a small number "1" and a "2". The plastic cam that the accel pump lever rides on is adjustable there. Also make sure you have minimum clearance between the spring/bolt on the end of the accel pump lever and the pump arm.