Rebuilt magnum 360 Noise

Take the valve covers off and see if there is oil splash on the inside of the covers. Where there’s none, the rocker has no oil.

Also run the engine with the valve covers off. Check to see oil at every rocker tip. Use rags to prevent oil spillage sir at least limit the oil spillage.

No oil? Check pushrods for clear oiling holes.
Check lifters for proper operation. Squishy lifters need to be fired.