Your oil pressure has to do with that noise its not supplying enough oil and its running dry I would not run the engine any more before you damage it more sounds like the oil pump is going out for your sake I would tear down the whole motor apart it sounds like a pretty bad rod knock and the fact about the oil pressure will make it worse
i have 22 lbs at idle with a brand new pump, so i don't see where 25lbs at idle is the norm, i ask a couple builders and they said it was fine. I have around 60psi at 3k though
Yeah I've talk to others who have said that they've had 10psi at idle and that's not a problem. Ford's gauge light won't come on until it's less than 5psi. For me, I'd be concern especially if you are having knocking sounds in the engine. Personally, mine is at or above 25psi at idle and I complete the rebuild of my engine in May '05 (only about 2300 miles on it) so the pump is fairly new. One thing I noticed is that the oil pressure with Synthetic oil is less than with Conventional Oil.
If and when you do rebuild don't be temped to install a HV oil pump unless you change to a 7quart oil pan - it would probably suck the stock pan dry to fast. Just One Man's Opinion.