I have some gears from a sporty pump, the same od but about a third wider. I thought it would be easy to correct the spacing problem by using a section from a puimp with a bad breather tower and once carefully aligned fitted with a couple of dowels. The drive gear could be counter bored to alow for the keys or a snap ring. Then, I was advised that it was all wasted thought, as the existing gears are capable of returning any reasonable amount of oil. Its seems that the real problem may be getting the oil to the pump. If anybody come up with a successful plan to get enough oil to the pistons and cylinders without ending up with a sump problem and without using some externally supplied skirt oiler, I would love to hear about it.