A understanding of what is actually happening inside the pump might help. This is only if you are not already aware though. For the drip test you are dealing with the position of the first elements piston in its bore. As it is travelling upward at a given point it cuts off its fuel supply port. This of course stops the drip. The fuel you are supplying to the pump body has some pressure so it is an available escape route for the fuel as long as it has some pressure and the supply port on that elements cylinder is open.

You are trying to get just slightly before that total cutoff point and for practical purposes are there when the fuel stream is being reduced and further upward movement of the piston results in the drip being reduced as well to almost nothing.

The fuel entrance point is again for all practical purposes almost totally closed off by the piston at that point. One complication that disturbs people is in how they are providing fuel for the test. It is perhaps better to use two people with one on the primer pump to provide a more uniform pressure for the test. Make sure you are turning the engine in the same direction as it runs to the 24 degree mark before the test. You can tell by the fan blade if uncertain.

Glad to hear they still indexed the pump on 84 and 85s. It was no longer a real requirement with the locating device for the pump on those years as far as I can accertain.

Someone that has timed a lot of these pumps maybe can chime in as well. You seem to be having some kind of difficulty I cannot quite relate to. You are advancing the throttle linkage for the test if recommended?
I see other people are posting some simular information as I just checked back on this thread. Good.

Concentrate on geting the new pump timed. When sure it is do not worry if power is still down. Since the index points still seem valid you probably had the pump timed right the last time.

The clue to the depressed power with the old pump is you had two pump elements numbers 4&5 dry if I remember. A good chance it is a fuel supply problem as you suspected just not the pump. I hope I am wrong yet many people have been down simular paths.

That existing problem might even affect the drip setting if you are pumping a lot of air into the pump..If things stay difficult gravity feed the pump from an elevated container for the drip test. You will get to the bottom of this.

Just do not get upset or frustrated during the process. At that point the thinking process departs for the majority of us. If in fact when working on something and it is tending to get on our nerves. It is best to leave it or put it aside for a short time. Usually amazing how much better things go when we get back to them after a short rest.