Just to be sure -
With your helper in the car, cranking it over, with the injector lines off, you're not seeing any fuel out of the lines at all? (Bearing in mind that we are talking small pulses, not some gushing flow)
And you have removed the plunger from the stop solenoid and put the solenoid back in place (without the plunger)
But, if you pump the lift pump with the banjo on the front of the injection pump loose, you get fuel come out all over the nose of the pump as you do the lever?
I'm guessing you have done the fuel filter, but, that's probably irrelevant if you can confirm that you have fuel coming out of that banjo on the front of the pump.
Can you just confirm all of the above, so we can be sure we are on the same page?
For the ease of it, you may as well take off the access hatch on the timing case front, that aligns with the fuel pump. Just to eyeball it and make sure it's spinning. I can't really see how the sprocket could spin and not the pump but you're this far in that you'll be taking that cover off soon enough anyway, and it's only 3 screws.
The reason I wanted to be so sure of the fuel supply is that the pump has a reservoir in it, and, if you've managed (somehow) to pump a load of air into it, it will take time to clear.
Also, if you've been up to stuff with the lift pump, they can be a pig to get to seal up properly and stop sucking in air.
Likely none of these are your issue though, but you have to check these things otherwise youre just going around in circles.
There is a lot to be said for making up some clear pipe for post lift pump connections. A couple of banjos and some clear nylon pneumatic pipe let you see exactly what's going on.
But, if it's a certainty that the injection pump has a good supply of fuel, AND it's a certainty that it's spinning, AND it's a certainty that the plunger is out of the solenoid and it's all back together again, AND still there's no fuel coming out of the output ports on the pump... Well that then sounds like the pump is stuffed.
One last thing to check, which I've never had a problem with, but a real life friend did (I can't remember how it manifests itself but we are clutching at straws now) -
The pump regulates it's internal pressure with a pinhole in the banjo bolt at the rear. Where the leak off pipes attach to the pump.
If you take out that bolt and look at it, it's not like the others. It has a pin hole in it. If that hole gets blocked the pump does odd things. I don't think it's your problem at all, but, if you have certainly ruled out all the rest (including air ingress from the lift pump olives that you've recently had undone) then it's probably the only thing to do before you conclude the pump is stuffed.
