1985 no oil pressure

I bought a 1985 mustang lx that had been sitting in a makeshift garage for 7 years. The car started and ran and had oil pressure when I trailered it home. I changed the oil and now the car has no oil pressure on the guage. I removed the distributor and ran the oil pump with a drill and can get oil through the push rods. I started the car with one valve cover off and oil ozzed through the push rods then stopped. The inside of the valve cover is coated with a black crust that is now breaking off.

1) Is this crust plugging up the oil pump pick up?
2) Should oil squirt out of the push rods while the engine is running?
3) Is the black crust carbon from blow by?
4) Any ideas how to solve this short of pulling the motor?

My first thought is to pull the oil pan clean everything,and replace the oil pump. Since that is no easy task I wanted to see if anyone had an alternate solution.

1) Is this crust plugging up the oil pump pick up?
It could, when you changed the oil did anything look bad coming out of the oil pan?

2) Should oil squirt out of the push rods while the engine is running?

It may not FLY OUT, depending on RPM, but it should not stop flowing... I know if you put a drill in there and turn it with that, the oil flys out of mine.. need to take cover. lol

3) Is the black crust carbon from blow by?

It could be... could be sludge, or old oil...

4) Any ideas how to solve this short of pulling the motor?

You could drop the pan, check the pickup... without pulling the entire motor....

Update

I hooked up a mechanical guage instead of dash guage. No oil pressure running the drill in reverse (counterclockwise). Ran the drill forward and heard a glug in the oil pan. Switched back to reverse and the pressure went right up to 50psi. Put the distributor back in and started car, it had good pressure for awile and began dropping and then none. Removed distributor ran pump backwards glug again. Switched back to counterclockwise and pressure back up to 40. It looks like i'm going to have to take the pan off and clean it out.

Great troubleshooting... good luck, take some pics and share them with us.