'68 318 - Coolant left in heads when removed.

Like said you dont have to run the chisel on the cast area of the block ( the freeze plug sealing surface) you punch through the plug it self then pull it with pliers.

But yes I agree its easy to mess up cast iron machined surfaces. it comes from not knowing. I'm sure when I was a kid i would have punched a screw driver through where it meets the freeze plug surface also . its what most would think to do...