Maybe an other head producer in the game.

tvt59 said
You port a lot of heads. Some of the castings from China are better than others and can be more extensively modified to make more power. The Bloomer heads on my engine make an honest 680hp. But according to Rod my heads only flow about 296 cfm on the intake. Hopefully the Engine pro heads are castings that cnc programs like Rods and others can be used on them. BTW I've heard that a couple of companies are thinking about casting SBM engine blocks. My fingers are crossed.

Way back when Vic Bloomer had a set of W5 heads on his bench pretty much identical to the ones that were on my motor.
They went right at 299.
So these heads going 296 is impressive, they make very similar power when compared to the same bench.
Obviously, numbers should be taken with a grain of salt.