If it were me, First having drained the coolant and oil refill the crankcase with diesel and run the engine for a few minutes to absorb the remaining coolant then drain.I would then pull the head and have it checked for flatness or damage with a machinist's straight edge and checked for cracks with dye penetrant or magnaflux. Your friendly machinist should be willing to help here. Surface head only if needed. Reassemble, refill and go with it hoping for the best. I've also done quickie crack checking by spraying with brake clean and wiping off. If there's a crack you'll see brake clean bleeding out of the crack.
