Good idea to park it for now. You should have good oil pressure at idle, I'd like to see 30-40 lbs myself. My big block had 60 at cruising speed with straight 50 weight oil.
Did you change the cam bearings? The oil holes have to line up with the corresponding holes in the block. Since you have a knock already, as someone else suggested, drop the pan and look at some of the main bearings. If you could isolate the knock to a particular cylinder, pop off the rod caps on that journal.
I think that your oil pump is the root of all your problems. The pickup tube might be loose at the pump casting. I never play with used oil pumps, they are cheap enough for a name brand one. I like to use a high volume one as opposed to a high pressure one. If the tube feels loose (yours may have fallen off) I stake it in place with a sharp punch. Pull the pump cover and look for metal shavings or heat discoloration, in any event, chuck that oil pump.
I hate to say it, but you're probably better off pulling the engine and putting it on an engine stand. Do you know how to use Plastigage for checking bearing clearances? Most good parts stores carry them and they do come with instructions, or you can ask here. Also take off your oil filter and hold it in a bench vise, cut the can off towards the base with a hacksaw. Look at the element closely, take it apart if you have to. If you see any appreciable amount of metal (more than a speck or 2), I would take the entire engine apart for a good inspection followed by a professional hot tanking.
Bob