valvetrain noise 5.9 magnum

I dont believe my block is ruined, everytime i have had the intake manifold off i have never seen any cracks anywhere, and i always torque my intake manifold bolts to 25 ft lbs. Never go anymore then that.
Also the timing chain has to be the original chain that was put in this engine when it was made, this engine is a 300hp crate 360 magnum purchased brand new in 2002. So i'm sure it has a double roller chain in it. And i have checked top dead center with a piston stop and my timing mark is dead on. So i dont think the chain has slipped.
And yes i do have a mechanical oil pressure gauage on it. The oil pressure has always been real good. When its at operating tempature the oil pressure will drop down to around 15 psi at idle, but as soon as you give it some gas it shoots up to 50 psi real quick, only when idling at operating tempature does it drop down to around 15 psi, wich i think is ok cause my idle rpm is 800.