If it were me and it's the bottom of the bore - not into water - I'd use a file or rotary file and smooth the edges, make sure there's not a "bump" around the fracture (making the bore too tight) and run it.
MOPER SMART!!!! If nothing else is damaged and you clear the pistons and rings then you should absolutely deburr the whole area that is broken. A stress crack can form in a microscopic crevice. After you grind/file the whole area that was broken then smooth it down real good with some med/fine sandpaper. You can't get it too smooth. The trick is to leave behind a surface that has NO SIGNS of a crack/fissure left over from the original break. Of course if it's in a non-stressed section of the block it's not as important to get it super smooth.
If you've ever seen someone drillstop a crack in cast iron you'll know what I'm talking about. Cracks (no matter how microscopic) can travel, with or without luggage LOL!!