200 inline 6 Mustang piercing squeak and knocking

[DON]

Just a thought and something to check: I had a starter bendex ( nose that goes in to the flex plate)interference with the flex plate. It made a terrible noise- metal to metal.
I should be easy to verify if this is the source and maybe you have eliminated this already

 

[drag-200stang]

The oil pan is very close to the crank, if the pan gets pushed up it will hit. Unlikely but the dip stick, if bent can hit the crank.

 

[Invectivus]

Did you use a double roller timing chain and maybe they jammed the oil slinger on?