I can help you out with the oil pump idea. We change out "External Drive Compressors" on air conditioners and there is a belt driven pump on the front of the housing. These pumps maintain 35 p.s.i. at 2500 rpm so I am sure that you will be running higher RPM's than that so obviously the p.s.i. will be higher. I would check with local scrap yards and see if they have any old compressors. There are many diff. types, so you want to find one that has a large pulley on the front and looks just like a car engine but smaller and behing that pulley is the pump connected to the crankshaft