Great comments, RandalPark. I suspect the return line might be closer to 3/8" rather than 5/8", just my gut suspicion, but I could be wrong. It's fine to get a length of hose that's a little longer than what you currently have, but not too long.
The genuine power steering hose will usually be stiffer and have a different feel and look than fuel line hose. I suggest that if the auto parts counter person questions that request for power steering spec hose, find someone that knows what you need and are talking about. Also you might take the old one for size reference. If you need to, don't forget to install some new hose clamps too and fresh power steering fluid.