You could make a plate for it to bolt to and test it with a flow meter. The plate would have to have ports into a reservoir (about $100 to build) and the flow meter (about $1200) could be put in-line with the output so that you could measure volume / pressure. That wouldn't do much good unless you could find the specs on the pump. If the gears fit the housing tightly and there is no perceptable wear it is probably good. I check the gears - ring OD too - and the bore in the body for scoring and wear. if there is more than .0005" wear I replace gears as long as the body is good. If it isn't good then you replace the pump.