nothing you posted seems out of the norm at all. All very believeable, except you say 3100 pounds, he says 3000 in another post.
Eddie’s have been proven to make around 600 horse well done. Those combinations aren’t more than that.
The Norm is different for different people. That's pretty quick for the stuff people throw away because they think it can't make power.
The OP was to make 600 HP and big dollar heads were bandied around when ported stockers or Eddies have done it. That dart is running 9.59 with only 275 cfm if that's true then its making 2.32 HP per cfm of airflow that's IMPRESSIVE in my view considering any W" head needs lots of expensive hardware to go with it.