Why is it being replaced are you in a rebuild process? Or are you just wanting to up your pressure. If the pump has failed, then you need to do more than replace the gears. If you want to up your pressure, then a booster plate may be the best choice.
Replacing The pump is not really what you will be doing. It is more like checking everything for the proper clearances. If the depth and diameter of the pocket on the front cover is not within specs then you will be looking for a new front cover. You will also have to check other clearances too like gear length,diameter, side clearance, and end clearance to the cover. these all contribute to a proper oiling system. It all depends on what the specific problem is that you want to fix.
Really need some more info to be able to help you out.