Still not sure what you meant by blow through. I am guessing there was a head gasket problem?
If that is the case then you may want to look at the heads, they could have the same kind of damage as well.
Before getting too carried away with getting it fixed, buy a fresh gasket and see if it will seal up. It looks to me like it may still have enough surface area to seal. Also, be sure to check that surface for flatness.
Was there a water leak before the manifold was pulled?
If the gasket will seal, then clean it up, and keep running it. A good coolant mix will help prevent further damage.