I'll bet you'll find things are way off egt and o2 wise with that 4150, no way should that motor pick up that much with a dominator.
I used to run them heads, they are decent out of box cnc'd but I ran them on a 358CI and nothing bigger, Id think your a bit over the limit with them but they still should get close to 610-625hp on a good honest dyno and more on a little happy of one.