That motor should make about 615 or so and have wall to wall torque...I think the cam spec is dead-on where 'd want it. I'm guessing the MCH heads flow around 315 @ 600....IIRC an out of the box street dominator only goes about 270 that's why porting pays off in the days where we have good heads.

Looking at the cam and your port area I'd have figured the torque peak to come in lower than 4900 (like around 4400) and the HP peak around 5300 but if you're cr is dead on 10.5 it should not start falling off too fast until 6000 or so. The way big (2 1/4) header isn't helping the cause either because wih those installed it took your motor more RPM to hit the sweet spot and the motor lost some momentum on the dyno below 4500... that's at least part of why your RPM peaks were on the high side of the RPM scale. You said you jetted up and it slowed down so I'm thinking you're restricted up top. for comparison mine ran a 1000hp with 84 + a pv primary and 90's in back. My cam was in at 107.

One of the best FLOWING out of the box Intakes is the Team G and it has really short runners that work well up high, can you borrow one and re-test? They're marginal for torque off idle to 4k on a street 440 (unless it's got a lot of compression) but on a 500 incher the torque at 3000 is still pretty decent.

you're about 50hp down from what it should be making pretty easy, did you get an HG/intake vacuum read on the pull? I'll bet it was too high (like 1 1/2" or so) and induction restricted.