Small block bottom build horsepower limit

Talked on Facebook with the guy who races that motor. He has 50 passes on it thus far.
Duster is 3000 with him in it, 904 trans. He has been best of 6.32 thus far at a bit over 108. He sad he would like to get it at a lower altitude, as the DA at his home track is typically over 7000 feet, and that is the only place it’s been raced thus far. Says he is still tuning on it.