I gave up scrounging and bought a 4 unit 19" rack housing from RS. (For US readers- I'm talking about RadioSpares, not Radio Shack.) The hardest part of this job was making the square holes for the meters. I started with a drill and electric jigsaw, then finished with a file.
Everything actually fits quite nicely so I'm glad I never bought a smaller box.
On the back are all the connections. The small blue and white sockets are Neutrik PowerCons rated at 20A 240V. With any luck, the white one won't mind getting 1000V shoved through it. The round fan hole was made by drilling a ring of 5mm holes, cutting with a jigsaw, and filing to size. It seemed to be easier than the meter holes, maybe the back is made of softer metal than the front?
Soon it'll be time to throw the big switch!