I think you're forgetting the wires? If you have one outlet with a 15-20A 120V circuit, then the wiring is almost certainly rated for 15-20A. If you just "combined" two 120V circuits into a 240V circuit, you still need an outlet that is rated for 30A, the wires leading to it also need to be rated for 30A, and it definitely needs a neutral. So you still need a new wire run if you don't have two 120V circuits right where you wanna plug in the box. To pass code you also may need to upsize conduit. If load is continuously near peak, it should be 50A instead of 30.
So basically you need a brand new circuit run if you don't have two 120V circuits next to each other. But if you're spending $65k on a single machine, an extra grand for an electrician to run conduit should be peanuts. While you're at it I would def add a whole-home GFCI, lightning/EMI arrestor, and a UPS at the outlet, so one big shock doesn't send $65k down the toilet.
