340 is knocking

70 cold 60 warm and it's steady. I'll check it again after the weekend and when I put the new header gaskets on. At least I'll have that part eliminated

That oil pressure sounds almost too good to be a bad rod bearing. Have you pulled the plug wire off the suspect cylinder while it`s running to see if the knock abates? I`d give that a try first, if the sound persist at the same level than maybe you can look elsewhere, perhaps a collapsed lifter or even a loose rocker lock nut.