Paint it white with a fungicidal oil-based primer such as Kilz.
Your big challenges are going to be climate control: Ventilation of a long narrow space can end up feeling like a wind tunnel, lol, and you are going to need to lay down shipping pallets to get the pots up off the cold cellar floor. Cold, wet roots will KILL an indoor plant faster than you would imagine. Expect to be hanging ducting and fans to keep air moving around the plants.

If you only plan to run the 600, GREAT. Block off a 4x4 space in the end of the hall. This is an ideal footprint for a HPS600 anyway. Hang 2 layers of panda film, about 3 feet apart, as a light-lock set of curtains that will allow you to easily enter the area, but still not let light through in the dark time. Go into the room with the lights off, but the lights in the basement on, and check for light leaks.

Don't forget to raise up the plants on a pallet! You can also circulate air under there to help discourage pests and mold.