I would check the wire coming from the VSS sensor @ 30 MPH. It should be 5-6 VAC.
If you have that voltage then maybe the PSOM is bad.
If so check for loose solder connection on the board.
I can email you a diagram of the Speedometer system if you like.
Most of the time it is a bad VSS or PSOM is why your Speedometer does not work.
Good luck on the water pump as that is a big job to get too.
You might want to read my post in this thread as you will need to remove the radiator first.
94-95 F53 radiator replacement
/