HID is an excellent option, you just need to have them in a proper enclosure or get one with a quartz envelope. I have some MH floodlights (250W) with what I think are ED28 bases (like a screw-in lightbulb but huge); the bulbs themselves have a thin glass envelope for safety and that blocks most but not all of the UV - they can still cause itchy eyes at close range.

If you bought a high quality T6 globe with quartz envelope (example), that would give you massive quantities of UV. Just be sure you replace it as soon as it shows any sign of cycling instead of staying on solidly; that's the end-of-life indication. With a good quality (Phillips or GE) globe that you replace as soon as it starts cycling, your chances of an explosion are probably not worth worrying about, even if they say T6 is for use in "enclosed fixtures only".

The other thing to consider if you're going to the expense of having a HID ballast etc, is that Mercury Vapour lamps produce more UV than Metal Halide, which are generally designed for a whitish light. In fact, it seems you can buy low pressure Hg lamps designed to produce 185nm and 253nm UV for the purpose of germicide and exposing litho plates, so they ought to be pretty perfect for carbon printing; example. You probably want the non-ozone-generating versions since ozone is a very strong oxidiser. And you want good (probably acrylic) shielding of your exposure box, or you will get skin and eye damage in short order.