I would replace the water pump.
Then the fan clutch/fan assy.

 

When I was a service manager with Rover, it was never mentioned that the 03/04 fan had better velocity. I have always suggested to people with failed 03/04 clutches to switch to an earlier D2 fan and there has never been an issue.

 

Is the 03/04 fan more or less identical to the D1, other than the fact the clutch is integrated?