I ran a best of 11.86 (real good air) with a 320 .533 lift mopar purple shaft HYD in a 3800 lb car with ported 906 was a real solid 12.0 to 12.1 car. Lash set so it lightly ticked setting adjustable pushrods is a PITA. Not sure if it was the heads or cam but liked 5800 to 6200 shifts best higher and it slowed down.
