Missed on this combo?

Looks to be giving up a bit early. I think your on the right track with knocking the cam back a few degrees and maybe a bigger carb. Are you jetting for A/F? That's just a tool, I would jet it until it looses power than back it off. Also carb spacers (can sometimes) do wonders, it may be what that intake needs to straighten out the air flow and turn it on. I know you don't plan on running one but the idea of a Dyno session is to literally try things to see what the motor responds too. How about the Dyno itself? Is it noted for being conservative? those are a rare commodity anymore with some of the numbers I see guys tossing around but, they do exist.