All right Al, here's the scoop. I called the Holley tech line (and man was I on hold for a long time to get through).
I finally got to talk to a person and asked him about the HP Series and the secondary power valve. He told me that all of the earlier HP carbs did not come equipped with a secondary power valve. It wasn't until a couple years after the dash one models came out (numbers with -1 after them) that they came with rear power valves. He says that all HPs now being manufactured have secondary power valves. So you must have a new or newer -1 model.
Like I mentioned earlier, I haven't bought a new one in a couple years now but the last one I got from Summit still did not have a secondary power valve. I usually block the secondary power valve anyway but I guess Holley got enough requests from their customers that they finally decided to offer the provision on their newer carbs. I still have a Holley HP 750 that I bought in the early 90s the day they were released for sale. I remember how excited everyone was that Holley decided to produce them.