I really wouldn't fire it until you get oil back into and onto all the engine part.Cranking it for as long as you did has squished all the pre-lube off of the bearings, cam lobes, and rockers.
I was laying in bed thinking of your problem(it's a sickness that good mechanics have) that pickup for the truck pan is pretty long it may take a drill and primer to get the oil up to the pump.
You may also have a stuck bypass valve and you might want to take the cap and spring out of the pump to remove the valve plunger to see if it moves easily.
Give me a call or text if you need my primer rod 330-256-1881
Gus