Different shape nose.-----Different bearing housing on front of the propshaft !!-----The bearing housing was made smaller as the nose of the gearcase is different !
Test components under the flywheel.----Charge coil and sensor coil.-----Flywheel does not need to be removed for this test.-----Explain " went to wide open throttle "------Checked flywheel key ?
Your location ?-----You might be able to adapt a Mercury outboard or Mercruiser stern dive pump and reservoir.-----The one that mounts inside the boat.
If it is the liquid mercury switch it prevents starting if motor is tilted all the way up.-----Shuts ignition off should you hit a log or sand bar at high speed.
Those 6 holes have nothing to do with flow to the pump.-----Yes usually the bottom hole is not covered by a screen.-----In my opinion these pumps are elegantly simple.----Hard to put one together with proper parts and it not work as a result of that work !