Non Mopar oil pressure oddity

Most Ford oil pressure gauges are not actual gauges. They are more or less go-no go indicators. If the engine has oil pressure it the gauge will stay more or less in the center of the range. It is not a linear gauge.

If it does not rattle on start-up it has oil pressure. You might try removing the oil pressure sending unit and see if it is gunked-up (technical term) on the end or in the end of the passage to it.