A CSV would make it hold 60 PSI steady and deliver any flow rate you need down to 1 GPM. It doesn't hurt to remove 3 or 5 impellers and leave the diffusers blank. But you will need spacers to fill the space on the shaft where the impellers came off. Spacers are impossible to find. You will need to grind off the impellers and leave the hub only to use as a spacer. Not a fun job, but it can be done.