Hi Ben,
Don't know if you have any engineering experience or machinery but here is some ideas to fit a pump.
I am not too familiar with Westbury's Warrior but it's more or less on the same principle as the Stuart D10.
1-- The first idea is to extend the shaft at the opposite end to the fly wheel and then make and fit the pump as per the pic of a D10.
2-- You could make and fit the spur gear drive as on Reeves Borderer
3--Another method is to machine an eccentric on the back of flywheel and mount a pump driven by the eccentric sheave as shown on this oscillating engine.
Hope this is of use to you and may give you some ideas how to fit a pump.
George.
