So I read the stupid dwarf tricks page on magmawiki, but other than that one thread linked there I couldn't find anyone who actually did this. The maximum range I observed was 6 tiles out, but it puts
so much lava out so fast that the seemingly small range doesn't matter. Almost immediately (maybe 10 seconds after this screenshot), I had a guesstimated 20x50 space
covered with lava. Also, notably, it's directly above the entrance to my fortress and under the pumps that pressurize it there's an airlock area filled with chained animals for thief detection as well as a bunch of cage traps.
If you want to see it in action,
here's the save. Sorry about the size but this is in a huge world. There's already a command to pull the firing lever. The adjacent lever cuts it off from its source, the nearby volcano. If not for the foresight of adding those floodgates, I wouldn't have been able to actually make it work.

It was nothing but a fancy lava-drip tube until I drained it and added the wall that seals off the space in between the pumps, so that the pressurized magma can't go anywhere but out.