cracked slant block

ok, so I don't know how it was missed during the clean up/re-ring. but yesterday while prepping for the replacement intake gasket to show up. we were checking for coolant leaks ( had a intake/exhaust stud leaking ). found a 1-2" crack in the block just above the pan rail.
my daughter was devastated. she was really looking forward to finally getting it out on the road. any downside to trying some sealer in the cooling system? would really like to re-use the head and cam. when I can swing a replacement. right now the funds are just not here to buy or rebuild another.