Crank breakers wanted

Garrett Ellison said
I believe you’ve got one of the good early blocks there, like my early crank is out of. That one may have 974 heads, too, but the ‘73 I got the rotating assembly out of had 576 heads on it.

Got the front clip off and a head pulled today. It is a ‘74 block with 974 heads. What makes those heads good?

The piston sure wasn’t havin a good time. The bore looked and feels untouched.