Hi again Jeremy!
Looking at your picture https://ibb.co/vWjJ3yT shows your oil didn't prime because you did not prime it. doh: You merely took off the oil filter and dabbed a gob of vaseline on the filter pickup. That will not prime your pump. If you had read my post, (sorry if you did and I was somehow unclear) you would have seen that you must pack the internal gears. You were nowhere near them

1. remove/divide the oil pump by removing its weird little screws. (These are different lengths..mark which is which as your remove them))

2. These LR/Rover have one section which is part of the timing cover and another section that #1 you must remove. The section that holds the gears, the oil filter, a tiny filter and pressure release valve come off. You must do so.

3. Once these screws are removed..the pump divides into two, possibly with a tiny bit of convincing if the gasket between the two sections is ancient. The pump gears will likely fall out. Prepare yourself for that. Have (a couple) of V8 oil pump gaskets at hand. https://l1nq.com/mnqhli5 When they are that cheap, buy two

4. Clean any remnants of the old gasket off...both sides.

5. b]You can now examine if the pump has traditional damage and decided whether you wish to repair it. SIMPLE or, like most people, let your oil pressure to keep falling over time. You are good either way. [[/b] https://www.gomog.com/TEMP/oilpumpWORN.jpg Nothing too serious here, but that damage is common and lowers your oil pressure. Easy to get rid of. Only parts suppliers tell us that these pumps can not be repaired.

6. Now use a tiny bit of non-hardening silicone on both surfaces, place the gasket on the part in your hand and place 2 of those nutty screws into two holes, spread apart. Put the pump section, screws and gasket to the side. Keep your big jar of vaseline at hand.

7. Now replace the gears again in the timing cover side and PACK them with vaseline. until it looks like this. https://www.gomog.com/TEMP/oilpumpjelly.jpg as I posted earlier. in this thread

8. While gingerly holding the gears in the timing cover, "offer up" the oil pump cover with the gasket and screws and turn the screws until the this cover holds on and supported. Gently add the other screws making sure they do not rip the gasket. Only 9 lbsft of torque for those little screws. . aka mildly firm.

GENERAL OBSERVATION. Yes. This can be a messy job. But with three Plus 8s, 3 decades and my mileage, I have done this job more times than I can remember. First time took me 2-3 hours, curses and 3 gaskets. But like anything, I can now do it in under 15 minutes. Please jot down your swearing for group entertainment.

Lorne

P.S. If you wish, I can walk you through it by ZOOM

P.P.S. I have also used the spin-the-gears from the distributor interface. I prefer the vaseline method. Removing the distributor to get access to the oil pump gears, means a precise re-timing of your ignition system. .