If you want to fix this the easy way, (not the right way), you could spray a good carb cleaner on the area to clean off residue coolant, then mix yourself up some two part epoxy from the parts house (comes in a twin tube syringe), and use a 16 penny nail to spread the epoxy around the freeze plugs/block, and it WILL seal the leak.
This may sound like a jerry rig fix, but hey... it'll work, and you won't have to pull the motor....