ALKY,
by a 2.3 Ford are you talking about a 2.3 liter ford engine?
If yes here is partial list of things to consider.
1) HP required? formula for figuring HP is GPM x PSI / (1714 x %efficency). For simplicity sake I use GPM x PSI / 1500.
another rule of thumb is it takes 1 HP to pump 1 GPM @ 1500 PSI
1a) To figure HP you must know flow in GPM and pressure in PSI.
2) Flow will be determined by pump displacement and RPM.
3) Pressure: some Vickers vane pumps are rated for 1500 PSI, some for 2500 PSI. Do you have the specs on the pump you have?
4) Like MMurphy stated. Pump rotation is critical. On most vane pumps, the rotation can be changed by dismantling the pump and flipping the rotating group. Don't try this if you don't know what you are doing though.
5) Vane pumps typically do not like belt drives or side loads on the input shaft. Some of them have outboard bearing to help absorb the side loads.
6) Coupling style: Several to choose from. Depends on the HP (torque), RPM environment they will be operating in etc. Love Joy, Magnaloy, Falk, etc all make flexible drive couplings.
7) mounting and alignment. Most flexible couplings will allow around .005 - .10" misalignment before starting to disintegrate.
I am sure others will add more items to consider.
Roy