340 dyno chart thoughts

Hard to say if things are "right" or usable to me. These are just my opinions...
It's not the rpm that caused the power dip. That torque dip shouldn't be present regardless of the headers used, small carb, or cam size. The engine never gets past 90% efficiency. It's pulling 1" of vacuum at peak torque. But the pressures look good and what I'd expect given the combo.
Overall, if it was mine, I'd be less than happy given the obvious expense and care taken on this engine. Vacuum will be low with those heads and that cam choice. vacuum won't be high enough to effectively work power brakes on a car that's street driven. Especially in stop and go traffic. In the end it's a lot of money to drop on a 340 that makes about 75hp more than a bone stock, machined and assembled in '70 340 did. And that 75 hp includes the dyno headers and no fuel pump parasitic loss. So in the chassis, with the alternator, fuel pump, smaller headers, and full exhaust, you're probably looking at a realistic 35-40hp over that stock 340, with a serious lack of vacuum. It's lazy.
Big negative influences could be the timing curve and the fuel the dyno guy runs.