Are these heads noted for cracking?
Yes
For some reason air can get trapped in the head when the cooling system is filled. By the time the engine is warm enough to open the thermostat, the head is hot. The incoming rush of water cracks the head.
To prevent this drill a 1/8" or bigger hole in your thermostat to allow air to escape as the system is being filled.
... but can the head be repaired?
I don't know.
