I've got a cerami-sealed modified engine in my car right now.
I've fixed many blocks(exterior cracks) with epoxy.
Welding will work for a while.
Stitching works too.
Best way not to spend much money IMO. grind out the crack and flash the oil out with a torch. Clean with mineral spirit's or the like and JB weld er up. Wait a few day's a nd use a bottle of glass sealer. If the crack isn't to bad it'll work probably through the winter. But in the end, you still got a crack.