Found my dads original 1971 duster!

So this machine shop / engine builder did a complete long block rebuild and missed a bad head and charged you another $680 bucks to fix their mishap? I would be having a problem with that and also would want to know exactly how hot they got my brand new motor on the dyno.

How the hell do you have internal blockage? I dirt dobber nest or what?

Did they get the motor so hot it cracked the head?
Ya. Again, I don’t know a lot about engines. His explanation to me was that there was no way they could have known. He gave me the old head to bring home. I was actually thinking that I hope it didn’t get too hot. But I just assumed they’d know what they were doing and it would have never gotten to a point where it would be hot enough to cause any issues. But again, I don’t even really know how engines work. Being honest