m20 -- no oil pressure -- need knowledge

[[1990]525]

Hi all. Recently I had the pleasure of uninstalling and reinstalling my cylinder head as I was getting a lot of coolant lost in oil. The procedure was standard, head milled etc. I also pulled the oil pan to clean out any gunk. After putting everything back together, it was time to turn the ignition. It started on the first try, but was very very rough. Two lights came on the oil pressure light and the check engine light. My dad figured that the oil pump may have lost its prime, but I think we decided that it should have primed itself after we started a few more times. There was really bad knock and we're under the impression that there is no oil pressure at all.

Tomorrow what should we do? So far all we can think is to pull the oil pan again, make sure the pump is alright and bolt it back up... or I think that the wiring harness may not be completely plugged in... If the harness was loose or not connected, would the car even start?
What could be the cause of the check engine light? Would that be related to the no oil pressure problem or?

Thanks for your ~knowledge~