Cam Talk

What Yellow Rose just said was pretty much spot on. I'm a believer that if you have to move the cam to make it "right", you have the wrong cam and if you have big gains with a spacer, you have the wrong intake. I deal in street engines first, race engines second. So they need to perform at all different levels. WOT is only run for bursts and represent a small percentage of total running time. If you are street driving this car, you might want to worry less about a specific HP number. With no other changes switching to RPMs will drop you 50+lbs over the front axle anyway... helping acceleration, weight transfer, and braking...lol. Just a thought there.
In terms of your dyno tests - I'm not questioning them - IMO they are where they should be.
12" at 1150rpm is not an idle - not sure of the carb choice but you're probably not on the idle circuit of it anyway.
I don't see a cam that similar making a 40+hp gain with a head like what you currently have. Because what you have is too close to maxing the heads' potential at this point. So a lot will depend on the Hughes program. If it were me, I would take their work, have it flowed by a shop I trust ('cause I don't trust Hughes), then have a cam designed to get me where I want to be. Stage III RPMs will exceed 600hp with cams a little bigger than you list, but it all comes back to what your exact heads can do.